481 research outputs found

    Microwave-Assisted Synthesis of Some 1H-1,2,4-Triazol-3-one Derivatives

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    4-Amino-5-(methyl/ethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one were synthesized from the reaction of (methyl/ethyl)-ester ethoxycarbonyl hydrazone with hydrazine hydrate and then, converted to corresponding Schiff bases using 9H-fluorene- 3-carbaldehyde. Ester, hydrazide and oxadiazole derivatives were synthesized starting from Schiff bases in three steps. All reactions occurred under conventional conditions and microwave irradiation. The obtained results were compared.KEYWORDS Triazole, oxadiazole, hydrazine hydrate, microwave irradiation

    El magmatismo de Atienza (NW de la Cordillera Ibérica): edad, origen y arquitectura del sistema magmático

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    A sill covering an area of more than 15 km2, several dykes up to 5 m thick and a volcanoclastic deposit crop out with similar petrology in the sector of Atienza (NW Iberian Chain, Spain). They consist of calc-alkaline porphyritic andesites with phenocrysts of plagioclase, amphibole, biotite, garnet and orthopyroxene. Based on U–Pb zircon analysis, an age of 290 ± 3 Ma (Sakmarian-Artinskian in the Cisuralian) has been calculated for this magmatism. The chemistry and geothermobarometry on amphibole crystals revealed crystallisation at different depths between 31 and 16 km, involving several events of magma recharge and fractional crystallisation. Magma ascent led to destabilisation of the amphibole crystals, their replacement by biotite, and the formation of thick microcrystalline coronas. Whole-rock trace element and isotopic compositions support a strong crustal influence in the origin of the magma. Crustal melting was produced by heating generated after lithospheric thinning, delamination, and asthenospheric rise produced after the uplift of the Variscan Orogen and the oroclinal folding of the Iberian Massif

    Characters of the Stephanian-Permian Bronchales basin and the tourmalinization associated to calc-alkaline rhyolites (Teruel Province)

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    [Resumen] La turmalinización que afecta a riolitas calco-alcalinas presentes en la fosa transtensional de Bronchales, con edad Autuniense, destaca por el elevado contenido en B (0.87 O/o de promedio). Esta mineralización muestra un enriqueciIl\iento de HREE y un empobrecimiento en LREE debido a que el fluido mineralizante (rico en F) pudo ejercer una función acomplejante para estos elementos y, también, con carácter selectivo, para As, Sn, Sb y Bi.[Abstract] Calc-alkaline rhyolites of Bronchales transtensional basin (Autunian age) are affected by a tourmalinization process. Tourmalinized rhyolites with 0.87 O/o ofboron as average value show As, Sb, Sn and Bi increments over nontourmalinized ones, as well as important enrichments of HREE over LREE possibly because tourmalinization fluids were enriched in complexing agents (i.e .F)

    Tuning the endocytosis mechanism of Zr-based metal−organic frameworks through linker functionalization

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    A critical bottleneck for the use of metal-organic frameworks (MOFs) as drug delivery systems has been allowing them to reach their intracellular targets without being degraded in the acidic environment of the lysosomes. Cells take up particles by endocytosis through multiple biochemical pathways, and the fate of these particles depends on these routes of entry. Here, we show the effect of functional group incorporation into a series of Zr-based MOFs on their endocytosis mechanisms, allowing us to design an effi-cient drug delivery system. In particular, naphthalene-2,6-dicarboxylic acid and 4,4'-biphenyldicarboxylic acid ligands promote entry through the caveolin-pathway, allowing the particles to avoid lysosomal degradation and be delivered into the cytosol, en-hancing their therapeutic activity when loaded with drugs

    Setting, Petrology and Geochemistry of the Volcanoclastic Complex of Orea (Guadalajara, Iberian Chain)

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    [Abstract] The volcanoclastic outcrop ofOrea (south margin of the Iberian Chain) reflects a pluriepisodic igneous activity, expressed in agglomerates and tuffs ofdacitic composition (with a calc-alkaline affinity) and Autunian-Thuringian age. The tuffs are the results' of a hydromagmatic activity, developed under a thin sheet of water (in a paludal environment). The structure of the magmatic outcrop results of the late-Hercynian extensional tectonics, equivalent to that observed in many other outcrops ofthe southeast border ofthe Iberian Chain. The setting characters and composition of the involved magmatic rock-types, suggest the presence of only one volcanic focus, as in other coetaneous half-grabens of this sector of the Iberian Chain

    Methane Emission Estimated from Different Cattle Intake Data in Heifers Grazing a Tropical Pasture

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    The quantification of methane (CH4) from enteric fermentation related to cattle diet is a useful tool to identify strategies to mitigate greenhouse gas emissions. This is even important in tropical and subtropical regions due to the lack of CH4 estimations in beef cattle, particularly from Bos Indicus breeds grazing tropical grasses (Kurihara et al., 1999). Several modelling approaches have been developed in order to predict CH4 emission. However, the use of these models has limitations associated with uncertainty information required such as feed intake (FI), composition of the selected diet and animal responses (Gonzalez et al., 2014). FI is the main factor influencing CH4 emission. Individual FI measurements are not easy to achieve accurately in grazing animals rather than those located in pens, particularly under deferred tropical pastures at the end of the dry season, due to the large proportion of death forage. In this case, cattle supplementation with energetic and proteins concentrates, is a viable practice in order to improve animal FI and reduce CH4 emissions. The main objectives of this study was estimate and compare CH4 emission using data collected from experimental trials and predicted by a model (UNFCCC, 2014) in supplemented heifers grazing low quality Chloris gayana pasture in northwestern Argentina (Semiarid Chaco Region)

    Effect of Supplementation Frequency on Forage Utilization by Heifers Grazing a Tropical Pasture during the Dry Season

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    In tropical pasture, low quality and availability forage during the dry season can limit the cattle intake. Energetic and protein supplementation is a viable practice to improve feed intake and animal performance. Previous studies have shown that infrequent protein supplementation decreases feeding cost achieving similar performance compared with every day supplementation (Farmer et al., 2004). Even though infrequent protein supplementation has been widely studied, little research has been carried out on infrequent energetic supplementation, especially its effect on pasture utilization. Some evidence indicates that negative effects on forage use at low levels of infrequent supplementation (Beaty et al., 1994). However, high levels of energetic supplementation can result in a substitution effect of forage for concentrate, reducing pasture utilization, even more when forage quality decreases as dry season progresses. Thus, the aim of this study was to evaluate the effect of supplementation frequency (continuous or discontinuous, based on energetic concentrate) on forage utilization by heifers grazing a Chloris gayana pasture during the dry season in the Semiarid Chaco Region (Northwestern Argentine)

    Triassic tholeiitic dolerites («ophites») of the El Grado diapir (Pyrenees, Huesca, Spain): emplacement and composition

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    Mesozoic dolerites in the south Pyrenean sector of El Grado (Huesca, Spain) preserve emplacement structures (fluidity structures at the top and load structures at the base) developed during their intrusion into unconsolidated marly-evaporitic Triassic sediments (Keuper facies). By analogy with other dolerites in the south Pyrenean domain, their emplacement age is equivalent to the uppermost Keuper facies terms, but prior to the final Triassic-early Liassic carbonated sediments. Radiometric ages (187-197±7 Ma) show that the emplacement occurred during the lower Liassic. The petralogical differentiation from the chilled margin facies to the central facies, and also to the late pegmatitoids, is consistent with that obtained from major elements, trace elements and REE. Their tholeiitic affinity, as defined by their geochemical composition, is equivalent to that of similar racks in the Pyrenean domain. However, the rocks analyzed here, which are located at the external sector of this domain, display a greater petralogical and geochemical differentiation as compared to similar rocks in the central sectors of the Pyrenean domain.Las doleritas mesozoicas del sector surpirenaico de El Grado (Huesca) conservan estructuras de emplazamiento (con desarrollo del movimiento de lava fluida al techo y de carga en su base) desarrolladas al instruir en los sedimentos margo-evaporíticos en facies Keuper, todavía inconsolidados. Por similitud con otras doleritas del dominio surpirenaico, la edad del emplazamiento es equivalente a la de los términos superiores de la facies Keuper y previa a la sedimentación carbonatada del Trías terminal-Lías inferior. Las determinaciones de edades radiométricas (187-197±7 Ma) indican que el emplazamiento debió tener lugar durante el Lías inferior. La diferenciación petralógica, desde la facies del borde enfriado a la central y, también, al posterior diferenciado pegmatoide concuerda con la obtenida con elementos mayores, trazas y REE. Su afinidad toleítica, definida por su composición geoquímica, coincide con la obtenida en rocas análogas para el dominio pirenaico; no obstante, estas rocas situadas en el borde más externo de dicho dominio representan una mayor diferenciación (petralógica y geoquímica) respecto a la obtenida, hasta el momento, para rocas análogas situadas en sectores más centrales del citado dominio pirenaico
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