502 research outputs found

    Quasar 3C 298: a test-case for meteoritic nanodiamond 3.5 µm emission

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    Aims. We calculate the dust emission expected at 3.43 and 3.53 µm if meteoritic (i.e. hydrogenated) nanodiamonds are responsible for most of the far-UV break observed in quasars. Methods. We integrate the UV flux that hydrogenated nanodiamonds must absorb to reproduce the far-UV break. Based on laboratory spectra of H-terminated diamond surfaces, we analyse the radiative energy budget and derive theoretically the IR emission profiles expected for possible C-H surface stretch modes of the diamonds. Results. Using as test case a spectrum of 3C 298 provided by the Spitzer Observatory, we do not find evidence of these emission bands. Conclusions. While diamonds without surface adsorbates remain a viable candidate for explaining the far-UV break observed in quasars, hydrogenated nanodiamonds appear to be ruled out, as they would give rise to IR emission bands, which have not been observed so far

    Phytoplankton, bacterioplankton and nitrate reductase activity distribution in relation to physical structure in the northern Alborán Sea and Gulf of Cadiz (southern Iberian Peninsula)

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    The IctioAlborán-Cadiz 95 cruise (July 1995) covered the northwest sector of the Alborán Sea, the Straits of Gibraltar and the Gulf of Cadiz. We present and discuss the distribution of phytoand bacterioplankton abundance, nitrate concentration and nitrate reductase (NR) activity according to circulation patterns described previously in the literature. The water-column integrated values of chlorophyll-a in the Alborán Sea were higher and more variable (12 to 318 mg m⁻³) than in the Gulf of Cadiz (3 to 49 mg m⁻³). This reflects the higher dynamism of the Alborán sector, related to the existence of characteristic mesoscale physical structures. The plankton (2-80 μm equivalent spherical diameter) in the upwelling region of the Alborán Sea had a biovolume 30 times higher than in the nutrient-poorer water of the Gulf of Cadiz. Large organisms were abundant and dominated the size spectrum of one coastal station in the Alborán zone, whereas the slope of the size spectrum became more negative at the Gulf of Cadiz station, as a consequence of the dominance of small cells. Bacterial abundance maxima ( 3 X 10⁶ bact ml⁻¹) also occurred in the upwelling region. We found relatively high nitrate and chlorophyll a concentrations in Cape Trafalgar's cold surface waters, probably due to the interaction between topography and strong tidal currents. The spatial pattern of the NR activity is discussed according to chlorophyll a, nitrate and bacteria distributions. The existence of high NR activity but low chlorophyll a and bacterial abundance suggests that this could be related with dissimilatory activity in large-sized particles.La campaña IctioAlborán-Cádiz 95 (julio de 1995) cubrió el sector noroeste del mar de Alborán, estrecho de Gibraltar y golfo de Cádiz. En este trabajo se presentan y discuten las distribuciones de abundancia de fitoplancton y bacterioplancton, concentración de nitrato y actividad nitrato reductasa (NR) de acuerdo con los patrones de circulación descritos en la bibliografía. Los valores de clorofila a integrados en la columna de agua en Alborán fueron mayores y más variables (12 a 318 mg/m³) que en el golfo de Cádiz (3 a 49 mg/m³). Esto refleja el mayor dinamismo de la zona de Alborán, relacionado con la existencia de estructuras físicas características a mesoescala. El análisis de la comunidad nano-microplanctónica (2-80 μm, diametro esférico equivalente) de la región de afloramiento del mar de Alborán mostró un biovolumen 30 veces mayor que el de aguas más pobres en nutrientes del golfo de Cádiz. Por otro lado, el espectro de tamaños en una estación costera de Alborán está dominado por organismos planctónicos grandes, mientras que la pendiente del espectro de tamaño se hace más negativa en una estación del golfo de Cádiz, como consecuencia de la mayor abundancia de plancton de pequeño tamaño. En la región de afloramiento se dieron también máximos de abundancia bacteriana ( 3 X 10⁶ bact ml⁻¹). Se han encontrado valores relativamente altos de nitrato y clorofila a en las frías aguas superficiales cercanas al cabo de Trafalgar, lo que se debe, probablemente, a la interacción entre topografía y fuertes corrientes mareales. Se discute el patrón espacial de la actividad NR en relación con las distribuciones de clorofila a, nitrato y bacterias. En muestras con valores elevados de actividad NR pero bajos de clorofila y abundancia de bacterias, se sugiere que esta actividad se relaciona con actividad disimilatoria en agregados de gran tamaño.Instituto Español de Oceanografí

    Numerical simulation of the open-pool reactor coolant system using a multi-domain approach

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    The computational simulation of large-scale reactors is currently limited by the high computational cost. The system codes allow addressing these problems, although with the well-known loss of local information. The use of coupling domains to reduce the problems looks like a proper alternative to settle this issue. In the present paper, a multi-domain coupling 3-dimensional/0-dimensional method to solve the thermal hydraulics of the TRIGA Mark I IPR-R1 reactor was implemented into a Finite Volume suite. Despite of the broadly literature about coupling methods, even in the nuclear engineering community, most of them manage with different codes in a fully explicit way. In the other hand, the benefit of solve different domain approaches inside the same software is in the use of monolithic algorithms. The proposed method consists on using 3-dimensional full CFD to simulate the reactor pool and 0-dimensional modelling for the external cooling loop. This is made by implementing a set of ad hoc dynamics boundary conditions to model the momentum and energy balances along the pipeline. This strategy was used to perform long-time steady state simulations of the reactor at the design power of 100 kW as well as for the repowering up to 265 kW. The results demonstrated that the core is efficiently cooled at the higher power without need to increase the coolant mass flow rate of the external system. Moreover, two accidental events were simulated: the first case was the Station Black Out at full power of 265 kW. The results indicated that the loss of the external heat sink led to a slow pool heating, but the core remains being cooled by the natural circulation in the pool. In fact, the mass flow rate through the core is only reduced in 15% by the loss of the external loop circulation. Finally, a large-Loss of Coolant Accident for the operational power of 100 kW and keeping the pump running is performed. In this case, the pool is quickly empty if safety systems do not take action and the core is uncovered after 450 s completely losing the core cooling capacity.Fil: Corzo, Santiago Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Godino, Dario Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Costa, Antonella Lombardi. Universidade Federal de Minas Gerais; Brasil. Conselho Nacional de Desenvolvimiento Científico e Tecnológico; BrasilFil: Reis, Patricia A. L.. Universidade Federal de Minas Gerais; Brasil. Conselho Nacional de Desenvolvimiento Científico e Tecnológico; BrasilFil: Pereira, Claubia. Universidade Federal de Minas Gerais; Brasil. Conselho Nacional de Desenvolvimiento Científico e Tecnológico; BrasilFil: Ramajo, Damian Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentin

    A Nonionic Alcohol Soluble Polymer Cathode Interlayer Enables Efficient Organic and Perovskite Solar Cells

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    The choice of interfacial materials and their properties play a critical role in determining solar cell performance and stability. For compatibility with roll-to-roll printing, it is desirable to develop stable cathode interface layers (CILs) that can be processed over the photoactive layer using orthogonal solvents. In this study, an n-type naphthalene diimide core and oligo (ethylene glycol) side-chain-based conjugated polymer is reported as a universal, efficient CIL for organic and perovskite photovoltaics. Besides good thermal stability and easy processing in alcohol/water, the new CIL is found to possess electron transport properties with an electrical conductivity of 2.3 × 10^{–6} S cm^{–1}, enabling its use as a CIL with a film thickness of up to ∼35(±2) nm. Utilizing the new CIL, 16% power conversion efficiency (PCE) is achieved for organic solar cells (OSCs) based on the PM6-Y6 photoactive layer (8.9% PCE for no CIL and 15.1% with state-of-the-art CIL, PDINO), and perovskite solar cells from methylammonium lead iodide yielded a PCE of 17.6%. Compared to the reference devices, the new CIL reduced trap-assisted carrier recombination and increased the built-in potential by 80 mV, simultaneously enhancing all photovoltaic parameters. Moreover, new CIL based devices had better photostability with no burn-in losses

    Fungal infections in patients after recovering from COVID-19: a systematic review

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    Background and aims: The presence of fungal infections has been described in patients after recovering from COVID-19. This study aims to conduct a systematic review of studies that reported fungal infections (Mucor spp., Pneumocystis jirovecii, or Aspergillus spp.) in adults after recovering from COVID-19. Methods: We performed a systematic review through PubMed, Web of Science, OVID-Medline, Embase, and Scopus. The study selection process was performed independently and by at least two authors. We performed a risk of bias assessment using the Newcastle–Ottawa Scale for cohort and case–control studies, and the Joanna Briggs Institute’s Checklists for Case Series and Case Reports. Results: The systematic search found 33 studies meeting all inclusion criteria. There was a total population of 774 participants, ranging from 21 to 87 years. From them, 746 developed a fungal infection. In 19 studies, Mucor spp. was reported as the main mycosis. In 10 studies, P. jirovecii was reported as the main mycosis. In seven studies, Aspergillus spp. was reported as the main mycosis. Regarding the quality assessment, 12 studies were classified as low risk of bias and the remaining studies as high risk of bias. Conclusion: Patients’ clinical presentation and prognosis after recovering from COVID-19 with fungal infection differ from those reported patients with acute COVID-19 infection and those without COVID-19 infection.Revisión por pare

    Una aplicaci?n de la teor?a del comportamiento planificado al segmento masculino latinoamericano de productos de cuidado personal

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    This research study identifies those factors which influence the consumption of care products in the Latinamerican male segment. That's why, an instrument based on the behavorial theory was applied to 600 men living in two countries of this regi?n and having different levels of development regarding the above mentioned category, Mexico -highly developed- and Peru -moderately developed-. The data obtained were analyzed using a model of structural equations. The results show that a subjective norm will stop men's consumption of these kinds of products. Similarly, the impact of this subjective norm will be lower in young men, allowing them to have a great aperture in the consumption of these care products.Este estudio busca identificar los factores que influyen en el consumo de productos de cuidado personal dentro del segmento masculino latinoamericano. Para ello, se aplic? un instrumento basado en la teor?a del comportamiento planificado a 600 hombres pertenecientes a dos pa?ses de la regi?n con diferentes niveles de desarrollo de la categor?a en cuesti?n: M?xico (alto desarrollo) y Per? (moderado desarrollo). Los datos obtenidos fueron analizados a partir de un modelo de ecuaciones estructurales. Los resultados sugieren que, en ambos pa?ses estudiados, la norma subjetiva inhibir?a el consumo de este tipo de productos entre los hombres. Asimismo, el impacto de la norma subjetiva ser?a menor en hombres j?venes, teniendo ellos mayor apertura al consumo de estos productos

    IC5063: AGN driven outflow of warm and cold gas

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    We present new ATCA 17- and 24-GHz radio images and ESO-NTT optical spectra of the radio-loud Seyfert galaxy IC5063, the first galaxy in which a fast (~ 600 km/s) outflow of neutral hydrogen was discovered. The new radio data confirm the triple radio structure with a central core and two resolved radio lobes. This implies that the previously detected fast outflow of neutral gas is occurring off-nucleus, near a radio lobe about 0.5 kpc from the core. The ionised gas shows complex kinematics in the region co-spatial with the radio emission. Broad and blueshifted (~ 500 km/s) emission is observed in the region of the radio lobe, at the same location as the blueshifted HI absorption. The velocity of the ionised outflow is similar to the one found in HI. The first order correspondence between the radio and optical properties suggests that the outflow is driven by the interaction between the radio jet and the ISM. Despite the high outflow velocities, no evidence is found for the ionisation of the gas being due to fast shocks in the region of the outflow, indicating that photoionisation from the AGN is likely to be the dominant ionisation mechanism. The outflow rate of the warm (ionised) gas is small compared to that of the cold gas. The mass outflow rate associated with the HI is in the same range as for ``mild'' starburst-driven superwinds in ULIRGs. However, in IC5063, the AGN-driven outflow appears to be limited to the inner kpc region of the galaxy. The kinetic power associated with the HI outflow is a small fraction (a few x 10^-4) of the Eddington luminosity of the galaxy but is a significant fraction (~ 0.1) of the nuclear bolometric luminosity. In IC5063, the outflows may have sufficient kinetic power to have a significant impact on the evolution of the ISM in the host galaxy.Comment: Accepted for publication in A&A, 11 pages, 8 figure
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