166 research outputs found

    Synthesis of Titanium and Zirconium Complexes with 2-Pyridonate and 2, 6-Pyridinedithiolate Ligands

    Get PDF
    Treatment of complex Cp2TiCl2] with the lithium salt of 2-hydroxypyridine afforded complex Cp2Ti(Opy)2] (1), whereas the same synthetic strategy applied to the analogous zirconium compound Cp2ZrCl2] did not worked. However, the use of the metallocene Cptt 2ZrMe2] with protic ligands allowed directing the reactivity towards protonation of the methyl groups attached to zirconium. To check this approach we reacted Cptt 2ZrMe2] with methanol affording complex Cptt 2ZrMe(OMe)] (2), which was characterized in situ by NMR techniques. In the same line, the reaction of Cptt 2ZrMe2] with 2-hydroxypyridine gave complex Cptt 2Zr(Me)(Opy)] (3)//forcing the conditions of this reaction did not lead to the expected complex Cptt 2Zr(Opy)2], most probably due to the steric hindrance exerted by the bulky cyclopentadienyl ligands. Further reactions of complex 3 with ligands having acidic protons also led to the recovery of the starting complex. However, when shifting to the bifunctional ligand 2, 6-dimercaptopyridine py(SH)2] a double protonation of the methyl ligands in Cptt 2ZrMe2] occurred, allowing the isolation of mononuclear complex Cptt 2Zr(¿S, ¿S, ¿N-pyS2)] (4), upon evolution of methane. The molecular structure of complex 4 was determined by X-ray methods, showing the zirconium atom in a highly distorted trigonal bipyramidal arrangement//structural parameters indicate a conventional Zr-N bond, but rather weak Zr-S interactions

    Feeding Habits of Wolffishes (Anarhichas denticulatus, A. lupus, A. minor) in the North Atlantic

    Get PDF
    Feeding habits of 7995 individuals of three wolffish species distributed in the north Atlantic were analyzed: 1016 of northern wolffish (Anarhichas denticulatus), 4783 of Atlantic wolffish (A. lupus) and 2196 of spotted wolffish (A. minor). The individuals sampled were taken in the NAFO Area Divisions 3NO in spring in the period 2002-2005, Div. 3L in summer in the period 2003-2004, Div. 3M in summer in the period 1993-2005, and in the ICES Area Div. IIb in autumn in the period 2004-2005. Feeding intensity was higher in the NAFO Area than in the northeast Atlantic (spring-summer vs. autumn), mainly in spotted wolffish in Div. 3M. The importance of each prey taxa was evaluated using the weight percentage. Wolffish species diet showed geographical differences. Ontogenic diet changes and prey variation through the studied period were observed, mainly in Atlantic and spotted wolffishes. This two species preyed primarialy on bottom (echinoderms, gastropods and bivalves) and benthopelagic (northern shrimp and redfish) organisms on Flemish Cap and Grand Bank. However fish and northern shrimp predation were more important on the Flemish Cap, mainly in spotted wolffish, showing periods with higher predation on these prey when the biomass of these prey species increased. This fact might have been the cause of diet overlap between Atlantic and spotted wolffishes in some periods in Div. 3M. Less ontogenic, annual and geographical diet variations were found in northern wolffish in NAFO Area, feeding mainly on ctenophores; however in Svalbard area, this species showed to be highly piscivore. Three species showed cannibalism but only in the Div. 3M

    Results for the Atlantic cod, roughhead grenadier, redfish, thorny skate and black dogfish of the Spanish Survey in the NAFO Div. 3L for the period 2003-2016

    Get PDF
    Since 2003, a stratified random spring bottom trawl survey was conducted by Spain in Division 3L of NAFO Regulatory Area (Flemish Pass). The surveys were carried out by the R/V “Vizconde de Eza” using bottom trawl net type Campelen. Entire series of mean catches, biomass and length distribution for Atlantic cod, roughhead grenadier, redfish, thorny skate and black dogfish are presented for the period 2003-2016.Postprin

    The mineralizing effect of zinc oxide-modified hydroxyapatite-based sealer on radicular dentin

    Get PDF
    Objective To evaluate the remineralization ability of three endodontic sealer materials at different root dentin regions. Material and methods Cervical, medial and apical root dentin surfaces were treated with two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite); an epoxy resin-based canal sealer, AH Plus; and gutta-percha. Remineralization, at the inner and outer zones of dentin disk surfaces, was studied by nanohardness (Hi) and Raman analysis. Nano-roughness and collagen fibrils width measurements were performed. Numerical data, at 24 h or 12 m, were analyzed by ANOVA and Student-Newman-Keuls (P<0.05). Results At the outer and inner zones of cervical dentin treated with oxipatite, the highest Hi after 12 m of immersion was achieved. The same group showed the highest intensity of phosphate peak, markers for calcification and crystallinity. Nanoroughness was lower and fibrils diameter was higher at the inner zone of dentin treated with oxipatite. Dentin mineralization occurred in every region of root dentin treated with oxipatite and calcypatite, especially at inner zone of dentin after 12 m. Conclusions Oxipatite, reinforced the inner root zone at any third of radicular dentin, by increasing both nanohardness and remineralization. When using calcypatite, the highest nanohardness was found at the apical third of the inner root dentin, but the lowest mechanical performance was obtained at the cervical and the medial thirds of the roots. Therefore, application of oxipatite as sealing cement of root canals is recommended. Clinical relevance Oxipatite, when used as endodontic sealing material, strengthens radicular dentin.Project MAT2017-85999-P MINECO/AEI/FEDER/UE supported by the Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (FEDER)

    Results for the Spanish Survey in the NAFO Regulatory Area of Division 3L for the period 2003-2015

    Get PDF
    Since 2003, a stratified random summer bottom trawl survey was conducted by Spain in the NAFO Regulatory Area of Division 3L (Flemish Pass). The surveys were carried out by the R/V “Vizconde de Eza” using bottom trawl net type Campelen 1800. Entire series of mean catches, biomass and length distribution for Greenland halibut, American plaice and witch flounder are presented for the period 2003-2015. Greenland halibut biomass and abundance estimates show an increasing trend since 2011, reaching the maximum values in the series in 2008 and 2014. In last years it can be seen a presence of juveniles (around 12-15 cm). American plaice biomass and abundance estimates present an increasing trend since 2010, reaching in 2015 the highest value in the series. Regarding witch flounder, the biomass and abundance increased in 2015, but there is no a clear trend in the whole period 2003-2015.Postprint0,000

    Parámetros reproductivos en el ganado vacuno de raza retinta explotado en dehesa: edad al primer parto e intervalo entre partos

    Get PDF
    La mejora de los caracteres reproductivos es de vital importancia para maximizar esta rentabilidad de las explotaciones de vacuno de carne, especialmente en las razas explotadas en régimen extensivo, como es el caso de la raza Retinta. Dicho sistema supone condiciones adversas e incluso extremas para los animales, especialmente durante la fase de recría fase fundamental y a la que generalmente se presta escasa atención en estas explotaciones. El objetivo del presente trabaja fue, analizar la posible influencia de distintos factores, tanto ambientales como genéticos, sobre la edad al primer parto (EPP) y el intervalo entre partos (IPP). Para ello hemos contando con los registros reproductivos correspondientes al Núcleo de Control de Rendimientos de la Raza Retinta. Estos incluían 2.786 primeros partos y 11.197 intervalos entre partos, correspondientes a 3. 112 vacas. Según nuestros resultados la edad al primer parto del ganado vacuno de raza Retinta se ve afectada por los factores ganadería de nacimiento, campaña y época de nacimiento, y la interacción de los tres. Dentro de estos factores, el factor ganadería absorbió del 52 al 66% de la variabilidad de la edad al primer parto. Otro factor que resulto significativo fue el tipo de alimentación que recibe la ternera durante el periodo predestete. Así mismo nuestros resultados muestras que dentro del rango de EPP estudiadas, no existe influencia sobre las condiciones de crecimiento del ternero de ese primer parto ni de los posteriores, incluso las novillas que paren a edad temprana (dentro de unos límites fisiológicos), produjeron más terneros y más pesados durante su vida. En cuanto al periodo medio entre partos encontramos una fuerte relación con la ganadería, y con el efecto campaña ganadera, correspondiendo los intervalos más largos a aquellos años en los que aparece un notable período de sequía. Independientemente a este factor, se aprecia una evidente disminución del IPP en la última década. El valor medio obtenido está fuertemente influenciado por el sistema de cubrición seguido (paridera restringida o continua). Según nuestros resultados las ganaderías con temporada de cubrición continua presentan menores intervalos, aunque con bajas diferencias, lo cual puede ser refleja de un manejo reproductivo menos optimizado que las de paridera estacional

    A zinc oxide-modified hydroxyapatite-based cement favored sealing ability in endodontically treated teeth

    Get PDF
    Objectives: To evaluate the effectiveness of different endodontic canal sealers for dentin permeability reduction and to determine the viscoelastic performance of root dentin after their application. Methods: Cervical, medial and apical root dentin surfaces were treated with two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite); an epoxy resin- based canal sealer, AH Plus; and gutta-percha. Root dentin was evaluated for fluid filtration. Field emission scanning electron microscopy, energy dispersive analysis, AFM, Young’s modulus and Nano-DMA analysis were also performed, at the inner and outer zones of dentin. Results: Dentin treated with oxipatite showed the lowest microleakage among groups with hermetically sealed tubules and zinc-based salt formations. Samples treated with oxipatite showed the highest Ei at the cervical dentin third among groups, at 6 m of storage. Oxipatite promoted the highest complex modulus and tan delta values at the inner zone of both cervical and medial root dentin. Calcypatite favored the lowest tan delta outcomes at the inner zone of apical dentin at 6 m. Conclusions: Specimens treated with oxipatite showed the highest sealing ability, based on the highest Young’s modulus and dentin mineralization, achieved by closing dentinal tubules, voids and pores that reinforced the inner zone of root dentin. The homogeneity of viscoelastic properties among the different root dentin thirds favored the energy dissipation without creating zones of stress concentration and micro-cracking which would have challenge micropermeability. Thereby, among the tested materials oxipatite is proposed as canal filling material and sealer in endodontics. Clinical Significance: Oxipatite could be considered a good candidate for root canal filling material and sealer due to its improved long-term sealing ability and to the advanced remineralization, and so to the enhanced energy dissipation achieved at the inner zone of the radicular dentin.This work was supported by the Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (FEDER). Project MAT2017-85999-P MINECO/AEI/FEDER/UE

    Radia2: A New Tool for Radiotherapy Verification

    Get PDF
    Radiotherapy is nowadays a proven technique in cancer treatments. Within the evolution of radiotherapy treatments towards more complex techniques, the need of new dosimetric methods for treatment verifications has appeared. In order to reach an improved dosimetric method, a collaboration was started to transfer knowledge from nuclear reaction instrumentation to medical applications, involving several departments from the University of Seville, Centro Nacional de Aceleradores (CNA), the Hospital Universitario Virgen Macarena and the company Inabensa. The first prototype, patent pending [2], gave very promising results. Currently, a critical review is being carried out to create an improved system

    Removal of 2-butoxyethanol gaseous emissions by biotrickling filtration packed with polyurethane foam

    Get PDF
    The removal of 2-butoxyethanol from gaseous emissions was studied using two biotrickling filters (BTF1 and BTF2) packed with polyurethane foam. Two different inoculum sources were used: a pure culture of Pseudomonas sp. BOE200 (BTF1) and activated sludge from a municipal wastewater treatment plant (BTF2). The bioreactors were operated at inlet loads (ILs) of 130 and 195 g m−3 hour−1 and at an empty bed residence time (EBRT) of 12.5 s. Under an IL of ∼130 g m−3 hour−1, BTF1 presented higher elimination capacities (ECs) than BTF2, with average values of 106 ± 7 and 68 ± 8 g m−3 hour−1, respectively. However, differences in ECs between BTFs were decreased by reducing the irrigation intervals from 1 min every 12 min to 1 min every 2 hours in BTF2. Average values of EC were 111 ± 25 and 90 ± 7 g m−3 hour−1 for BTF1 and BTF2, respectively, when working at an IL of ∼195 g m−3 hour−1. Microbial analysis revealed a significant shift in the microbial community of BTF1 inoculated with Pseudomonas sp. BOE200. At the end of the experiment, the species Microbacterium sp., Chryseobacterium sp., Acinetobacter sp., Pseudomonas sp. and Mycobacterium sp. were detected. In BTF2 inoculated with activated sludge, the denaturing gradient gel electrophoresis (DGGE) technique showed a diverse microbial community including species that was able to use 2-butoxyethanol as its carbon source, such as Pseudomonas aeruginosa and Pseudomonas putida as representative species. Although BTF1 inoculated with Pseudomonas sp. BOE200 and higher gas velocity (probably greater gas/liquid mass transfer rate) showed a slight improvement in performance, the use of activated sludge as inoculum seems to be a more feasible option for the industrial application of this technology

    A review of NAFO 3LMN roughhead grenadier (Macrourus berglax Lacepède, 1801) reproductive biology including the evaluation of maturity ogive estimates.

    Get PDF
    A collection of 4770 histological slides collected in NAFO divisions 3LMN in a depth range from 200 to 1500 m and covering a time period between 2001 and 2015, has been reviewed to obtain information on reproductive biology of Macrourus berglax. Especial attention has been paid in atresia because its potential impact on stock productivity. Spatial and temporal variability of size and age at maturity of female roughhead grenadier was analyzed in NAFO divisions 3LMN based on microscopic maturity staging and individual age readings. Spawning capable females are homogeneously distributed nearly year-round, but in scarce numbers what prevent to define a spawning season. This statement united to the high levels of atresia could indicate a reproductive migration. We observed a clear decrease in length at first maturity (L50) of females from 27.8 cm in the period 2005-2011 to 25.6 cm in the last four years. The age at first maturity, A50, varied between 13.1 and 15 years, and there is not an evident trend of change over the years.Postprint0,000
    corecore