2,499 research outputs found

    The abundances of polyacetylenes towards CRL618

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    We present a mid-infrared high spectral resolution spectrum of CRL618 in the frequency ranges 778-784 and 1227-1249 cm^-1 (8.01-8.15 and 12.75-12.85 um) taken with the Texas Echelon-cross-Echelle Spectrograph (TEXES) and the Infrared Telescope Facility (IRTF). We have identified more than 170 ro-vibrational lines arising from C2H2, HCN, C4H2, and C6H2. We have found no unmistakable trace of C8H2. The line profiles display a complex structure suggesting the presence of polyacetylenes in several components of the circumstellar envelope (CSE). We derive total column densities of 2.5 10^17, 3.1 10^17, 2.1 10^17, 9.3 10^16 cm^-2, and < 5 10^16 cm^-2 for HCN, C2H2, C4H2, C6H2, and C8H2, respectively. The observations indicate that both the rotational and vibrational temperatures in the innermost CSE depend on the molecule, varying from 100 to 350 K for the rotational temperatures and 100 to 500 K for the vibrational temperatures. Our results support a chemistry in the innermost CSE based on radical-neutral reactions triggered by the intense UV radiation field.Comment: 9 pages, 4 figures, 1 table; accepted for publication in The Astrophysical Journa

    Valorisation of ilmenite mud waste in the manufacture of commercial ceramic

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    This paper reports the results of a study focused on the production of ceramic tiles from ilmenite mud (MUD), a waste generated by the industry devoted to the TiO2 pigment production. Ceramic tiles were produced from mixtures of a commercial red stoneware mixture (RSM) with different concentrations of mud (3, 5, 7, 10, 30 and 50 wt.%). The samples were sintered to simulate a fast-firing process. The sintering behaviour of the fired samples was evaluated according to ISO methodologies by linear shrinkage, water absorption and porosity measurements. Both green powder and fired samples were characterised by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC/TG), field emission scanning electron microscopy (FESEM) and bending strength measurements. Moreover, since this activity is a NORM (Naturally Occurring Radioactive Material) industry, the radionuclides activity concentrations were measured by both gamma and alpha spectrometry techniques. Finally, the TCLP leaching test (Toxicity Characteristic Leaching Procedure, USEPA) was performed to assess the risks of the use of undissolved mud tiles from an environmental perspective. The results obtained demonstrated that ilmenite mud can be successfully valorisated in the manufacture of red stoneware ceramic bodies, with even better technological properties than commercial ones. The addition of mud as additive (from 3% to 10%) had a beneficial effect to the sintering processes, improving the bending strength (up to 15%) and reducing both apparent porosity and water absorption (up to 50%).This research has been partially supported by the Government of Andalusiás Project “Characterization and modelling of the phosphogypsum stacks from Huelva for their environmental management and control” (Ref.: RNM-6300) and by National Institution of Higher Education, Science, Technology and Innovation of the Republic of Ecuador – (SENESCYT for its acronym in Spanish), Prometeo Project. Dr. M.I. Martín expresses her gratitude for the contract JAE-Doc_08-00032 to the Spanish National Research Council (CSIC), co-financed by the European Social Fund Operational Programme 2007–2013 Adaptability and Employment Multiregional.Peer reviewe

    Molecular characterization of autophagic and apoptotic signaling induced by sorafenib in liver cancer cells

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    Sorafenib is the unique accepted molecular targeted drug for the treatment of patients in advanced stage of hepatocellular carcinoma. The current study evaluated cell signaling regulation of endoplasmic reticulum (ER) stress, c-Jun-N-terminal kinase (JNK), Akt, and 5′AMP-activated protein kinase (AMPK) leading to autophagy and apoptosis induced by sorafenib. Sorafenib induced early (3–12 hr) ER stress characterized by an increase of Ser51P-eIF2α/eIF2α, C/EBP homologous protein (CHOP), IRE1α, and sXBP1, but a decrease of activating transcription factor 6 expression, overall temporally associated with the increase of Thr183,Tyr185P-JNK1/2/JNK1/2, Thr172P-AMPKα, Ser413P-Foxo3a, Thr308P-AKt/AKt and Thr32P-Foxo3a/Foxo3a ratios, and reduction of Ser2481P-mammalian target of rapamycin (mTOR)/mTOR and protein translation. This pattern was related to a transient increase of tBid, Bim EL, Beclin-1, Bcl-xL, Bcl-2, autophagy markers, and reduction of myeloid cell leukemia-1 (Mcl-1) expression. The progressive increase of CHOP expression, and reduction of Thr308P-AKt/AKt and Ser473P-AKt/AKt ratios were associated with the reduction of autophagic flux and an additional upregulation of Bim EL expression and caspase-3 activity (24 hr). Small interfering-RNA (si-RNA) assays showed that Bim, but not Bak and Bax, was involved in the induction of caspase-3 in sorafenib-treated HepG2 cells. Sorafenib increased autophagic and apoptotic markers in tumor-derived xenograft model. In conclusion, the early sorafenib-induced ER stress and regulation of JNK and AMPK-dependent signaling were related to the induction of survival autophagic process. The sustained drug treatment induced a progressive increase of ER stress and PERK-CHOP-dependent rise of Bim EL, which was associated with the shift from autophagy to apoptosis. The kinetic of Bim EL expression profile might also be related to the tight balance between AKt- and AMPK-related signaling leading to Foxo3a-dependent BIM EL upregulation.Ministerio de Economía y Competitividad BFU2016‐75352‐PInstituto de Salud Carlos III PI15/00034, PI13/ 00021, PI16/00090, PI14/01349Ministerio de Educación FPU16/05127, FPU12/01433, FPU13/01237Junta de Andalucía CTS-6264, PI-00025-2013, PI-0127-2013, PI-0198-201

    Hemangioma intramuscular: A propósito de un caso

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    Se presenta el caso de un tumor de partes blandas localizado en la unión de tercio proximal y medio de pierna derecha, en el espesor del músculo peroneo lateral largo. Los estudios preoperatorios consideraron como primera posibilidad un hemangioma que fue confirmado posteriormente en la anatomía patológica y tratado mediante resección completa. Se hace a su vez un recuerdo bibliográfico de este tipo de tumores.A soft-tissue located in the confluence of the proximal and middle third of the right leg, depth in the peroneus lateralis longus muscle is presented. Preoperative showed an intramuscular haemangioma and postoperative histological diagnosis was confirmed and complete excision was the treatment applied. The literature related to the condition is also reviewed

    Volterra operators and semigroups in weighted Banach spaces of analytic functions

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    We characterize the boundedness, compactness and weak compactness of Volterra operators Vg( f )(z) := z 0 f (ζ )g (ζ ) dζ acting between different weighted spaces of type H∞ v in terms of the symbol function g, for the case when v is a quasi-normal weight, a notion weaker than normality. Then we apply the characterization of compactness to analyze the behavior of semigroups of composition operators on H∞ v

    Inherently Safer Design and Optimization of Intensified Separation Processes for Furfural Production

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    Currently furfural production has been the subject of increased interest because it is a biobased chemical able to compete with fossil-based chemicals. Furfural is characterized by flammability, explosion, and toxicity properties. Improper handling and process design can lead to catastrophic accidents. Hence it is of most importance to use inherent safety concepts during the design stage. This work is the first to present several new downstream separation processes for furfural purification, which are designed using an optimization approach that simultaneously considers safety criteria in addition to the total annual cost and the eco-indicator 99. The proposed schemes include thermally coupled configuration, thermodynamic equivalent configuration, dividing-wall column, and a heat integrated configuration. These are compared with the traditional separation process of furfural known as the Quaker Oats Process. The results show that because of a large amount of water present in the feed, similar values are obtained for total annual cost and eco-indicator 99 in all cases. Moreover, the topology of the processes has an important role in the safety criteria. The thermodynamic equivalent configuration resulted as the safest alternative with a 40% reduction of the inherent risk with respect to the Quaker Oats Process, and thus it is the safest option to purify furfural

    High pressure theoretical and experimental analysis of the bandgap of BaMoO4, PbMoO4, and CdMoO4

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    We have investigated the origin of the bandgap of the BaMoO4, PbMoO4, and CdMoO4 crystals on the basis of optical absorption spectroscopy experiments and ab initio electronic band structure, density of states, and electronic localization function calculations under high pressure. Our study provides an accurate determination of the bandgaps Eg and their pressure derivatives dEg/dP for BaMoO4 (4.43 eV, -4.4 meV/GPa), PbMoO4 (3.45 eV, -53.8 meV/GPa), and CdMoO4 (3.71 eV, -3.3 meV/GPa). The absorption edges were fitted with the Urbach exponential model which we demonstrate to be the most appropriate on thick crystals with direct bandgaps. So far, the narrowing of the bandgap of distinct PbMoO4 had been qualitatively explained considering only the presence of the Pb 6s levels at the top of its valence band. Its fast pressure dependent redshift and the occurrence of its direct bandgap away from Γ in contrast to the other scheelites had remained unsolved. Here we show that contrary to what had been proposed and differently to the other scheelites, in PbMoO4 the band gap takes place between the Pb 6s levels at the top of the valence band and the antibonding O 2p levels at the bottom of the conduction band. For this reason the direct bandgap is pushed away from zone center in order to allow s − p mixing. Its pressure dependence is one order of magnitude faster than in the other shceelites due to two effects: its delocalized character and the higher compressibility of dodecahedral units, PbO8, compared to tetrahedral units, MoO4

    Effective nonlinear model for electron transport in deformable helical molecules

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    The helical conformation of electric dipoles in some chiral molecules, such as DNA and bacteriorhodopsin, induces a spin-orbit coupling that results in a sizable spin selectivity of electrons. The local deformation of the molecule about the moving electron may affect the spin dynamics due to the appearance of bright solitons with well-defined spin projection onto the molecule axis. In this work, we introduce an effective model for electron transport in a deformable helical molecular lattice that resembles the nonlinear Kronig-Penney model in the adiabatic approximation. In addition, the continuum limit of our model is achieved when the dipole-dipole distance is smaller than the spatial extent of the bright soliton, as discussed by E. Diaz et al. [N. J. Phys. 20, 043055 (2018)]. In this limit, our model reduces to an extended Davydov model. Finally, we also focus on perturbations to the bright soliton that arise naturally in the context of real helical molecules. We conclude that the continuum approximation provides excellent results in more complex scenarios

    Ara militaris en el centro-occidente de Veracruz: registros recientes

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    Based on interviews and field observations, we present information about individuals of Military Macaw (Ara militaris) in the common of Caballo Blanco, in central western of Veracruz. We obtained observations in 2014 and 2015 on a site with cliffs covered by deciduous forest relicts. However, local people said they had seen Military Macaws in this area at least since 2012. It is important to continue working with the people of Caballo Blanco in order to ensure the preservation of this population of Military Macaw. Also, it is necessary to deepen aspects of their ecology on this site, which would be the only one with recent and constant presence of this species in Veracruz.RESUMEN. Con base en entrevistas y observaciones de campo, presentamos información sobre individuos de la guacamaya verde (Ara militaris) en la comunidad de Caballo Blanco, en el centro occidente de Veracruz. Se obtuvieron observaciones en 2014 y 2015 en un sitio con acantilados cubiertos por relictos de bosques caducifolios. Sin embargo, la población local dijo que había visto guacamayas verdes en esta área por lo menos desde 2012. Es importante seguir trabajando con la gente de Caballo Blanco para asegurar la preservación de esta población de guacamayas verdes. Además, es necesario profundizar aspectos de su ecología en este sitio, que sería el único con presencia reciente y constante de esta especie en Veracruz.

    Shellfish Exploitation in the Western Canary Islands Over the Last Two Millennia

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    The residents of the Canary Archipelago consumed limpets since the arrival of humans ∼2500 yrs. ago, and these harvested gastropods were deposited in large coastal shell middens. This work preliminarily explores shell margin oxygen isotope composition (δ18O) and body size of the black limpet (Patella candei d’Orbigny, 1840) from archaeological sites in the Canary Islands to assess possible seasonal variability and intensity of shellfish collection throughout the late Holocene. The shell margin δ18O values of 100 shells (radiocarbon dated between ∼500 and ∼1800 cal. yr BP) were analysed to estimate sea surface temperature (SST) at time of death. Paleotemperature estimates suggest shellfish harvesting was not year-round, and was avoided in the cooler months (when SST &lt; 20°C). This pattern differs from most higher latitude Mesolithic and Neolithic human groups, which gathered shellfish year-round, targeting winter more heavily. Preliminary body-size measurements suggest shell sizes have experienced a decline from aboriginal times to the present, which possibly resulted from increasing anthropogenic pressures. During aboriginal inhabitation, maximum adult shell size remained stable, suggesting that present-day harvesting practices are more intense than harvesting from aboriginal human groups. This intensive collection has likely diminished the average adult size of limpet populations in the islands by ∼27%
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