ABSTRACT
We study the global star formation rate (SFR) versus stellar mass (M*) correlation, and the spatially resolved SFR surface density (ΣSFR) versus stellar mass surface density (Σ*) ...correlation, in a sample of ∼2000 galaxies from the MaNGA MPL-5 survey. We classify galaxies and spatially resolved areas into star forming and retired according to their ionization processes. We confirm the existence of a star-forming main sequence (SFMS) for galaxies and spatially resolved areas, and show that they have the same nature, with the global as a consequence of the local one. The latter presents a bend below a limit Σ* value, ≈3 × 107 M$\odot$ kpc−2, which is not physical. Using only star-forming areas (SFAs) above this limit, a slope and a scatter of ≈1 and ≈0.27 dex are determined. The retired galaxies/areas strongly segregate from their respective SFMSs, by ∼−1.5 dex on average. We explore how the global/local SFMSs depend on galaxy morphology, finding that for star-forming galaxies and SFAs, there is a trend to lower values of star formation activity with earlier morphological types, which is more pronounced for the local SFMS. The morphology not only affects the global SFR due to the diminish of SFAs with earlier types, but also affects the local SF process. Our results suggest that the local SF at all radii is established by some universal mechanism partially modulated by morphology. Morphology seems to be connected to the slow aging and sharp decline of the SF process, and on its own it may depend on other properties as the environment.
Five new rare-earth coordination polymers (CPs) were designed in order to offer a remarkable platform that contains light-harvesting antennas and catalytic active centers to achieve solar-energy ...conversion as green alternatives in the synthesis of imines. These five new spirobifluorene-containing Ln-CPs, named Er3(Hsfdc)3(sfdc)3(H2O)·xH2O (RPF-30-Er), Ln(Hsfdc)(sfdc)(EtOH)·S (RPF-31-Ln, where Ln = La, Nd, and Sm and S = H2O or EtOH), and Ho(Hsfdc)(sfdc)(H2O) (RPF-32-Ho) (RPF = rare-earth polymeric framework and H2sfdc = 9,9′-spirobi9H-fluorene-2,2′-dicarboxylic acid), have been solvothermally synthesized, and their structural features can be described as follows: (i) RPF-30-Er shows a 3D framework in which the inorganic trimers (secondary building units) are cross-linked by Hsfdc– and sfdc2– linkers displaying a pcu topology. (ii) The isostructural RPF-31-Ln series of materials, together with RPF-32-Ho, exhibit a 1D network of chains growing along the a axis with a ribbon-of-rings topology type. The photocatalytic activity of the RPF-n materials was tested in the oxidative coupling of amines using molecular oxygen and air as oxidizing agents under warm light. Among the materials investigated, RPF-31-Nd was chosen to further investigate the approach in the selectivity of different amine derivates.
The stable dispersion of graphene flakes in an aqueous medium is highly desirable for the development of materials based on this two-dimensional carbon structure, but current production protocols ...that make use of a number of surfactants typically suffer from limitations regarding graphene concentration or the amount of surfactant required to colloidally stabilize the sheets. Here, we demonstrate that an innocuous and readily available derivative of vitamin B2, namely the sodium salt of flavin mononucleotide (FMNS), is a highly efficient dispersant in the preparation of aqueous dispersions of defect-free, few-layer graphene flakes. Most notably, graphene concentrations in water as high as ∼50 mg mL–1 using low amounts of FMNS (FMNS/graphene mass ratios of about 0.04) could be attained, which facilitated the formation of free-standing graphene films displaying high electrical conductivity (∼52000 S m–1) without the need of carrying out thermal annealing or other types of post-treatment. The excellent performance of FMNS as a graphene dispersant could be attributed to the combined effect of strong adsorption on the sheets through the isoalloxazine moiety of the molecule and efficient colloidal stabilization provided by its negatively charged phosphate group. The FMNS-stabilized graphene sheets could be decorated with nanoparticles of several noble metals (Ag, Pd, and Pt), and the resulting hybrids exhibited a high catalytic activity in the reduction of nitroarenes and electroreduction of oxygen. Overall, the present results should expedite the processing and implementation of graphene in, e.g., conductive inks, composites, and hybrid materials with practical utility in a wide range of applications.
ABSTRACT
We report on the first simultaneous high-time resolution X-ray and infrared (IR) observations of a neutron star low mass X-ray binary in its hard state. We performed $\approx 2\,$ h of ...simultaneous observations of 4U 1728−34 using HAWK-I@VLT, XMM–Newton, and NuSTAR. The source displayed significant X-ray and IR variability down to sub-second time-scales. By measuring the cross-correlation function between the IR and X-ray lightcurves, we discovered a significant correlation with an IR lead of $\approx 30 \!-\! 40\,$ ms with respect to the X-rays. We analysed the X-ray energy dependence of the lag, finding a marginal increase towards higher energies. Given the sign of the lag, we interpret this as possible evidence of Comptonization from external seed photons. We discuss the origin of the IR seed photons in terms of cyclo-synchrotron radiation from an extended hot flow. Finally, we also observed the IR counterpart of a type-I X-ray burst, with a delay of $\approx 7.2\,$ s. Although some additional effects may be at play, by assuming that this lag is due to light travel time between the central object and the companion star, we find that 4U 1728−34 must have an orbital period longer than $3\,$ h and an inclination higher than 8○.
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The COVID-19 pandemic may have adversely affected the early diagnosis of skin cancer.
To compare epidemiological, clinical and histopathological characteristics in patients undergoing ...cutaneous squamous cell carcinoma (SCC) surgery before and after the beginning of the pandemic.
We conducted a cross-sectional study including two case series: (1) patients operated on for SCC in the year after the first state of alarm in Spain (15 March 2020), and (2) patients with SCC operated on in the previous year. Epidemiological, clinical and histopathological variables, tumour stage and risk grade were collected.
248 patients were included (127 undergoing surgery before the pandemic and 121 after the pandemic). After the beginning of the pandemic, the percentage of high-risk SCC significantly increased from 35.3% to 46.2% (p=0.011). However, no significant differences were found in thickness, perineural invasion or metastases.
Although there has not been a significant reduction in the number of SCC operated on after the pandemic, there has been a significant increase in high-risk SCC. All this could lead to an increase in skin cancer mortality in the future.
La pandemia de COVID-19 ha podido afectar negativamente el diagnóstico precoz del cáncer de piel.
Comparar las características epidemiológicas, clínicas e histopatológicas en los pacientes intervenidos de carcinoma de células escamosas (CCE) cutáneo antes de la pandemia y después del inicio de la pandemia.
Se diseñó un estudio transversal que incluía 2 series de pacientes: 1) pacientes intervenidos de CCE el año posterior a la declaración del confinamiento general en España (15 de marzo de 2020), y 2) pacientes intervenidos de CCE el año previo. Se recogieron variables epidemiológicas, clínicas e histopatológicas, así como el estadio tumoral y el grado de riesgo.
Se incluyeron 248 pacientes (127 intervenidos antes de la pandemia y 121 intervenidos después de la pandemia). Tras el inicio de la pandemia, el porcentaje de CCE de alto riesgo aumentó significativamente de 32,3 a 45,5% (p=0,011). No obstante, no se encontraron diferencias significativas en el grosor tumoral, la invasión perineural o la presencia de metástasis.
Aunque no se produjo una reducción significativa en el número de CCE intervenidos después de la pandemia, ha habido un incremento significativo en los CCE de alto riesgo. Todo ello puede conllevar un incremento en la mortalidad por cáncer de piel en el futuro.
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