Faint emission lines in the Galactic H II regions M16, M20 and NGC 3603

We present deep echelle spectrophotometry of the Galactic {\hii} regions M16, M20 and NGC 3603. The data have been taken with the Very Large Telescope Ultraviolet-Visual Echelle Spectrograph in the 3100 to 10400 \AA range. We have detected more than 200 emission lines in each region. Physical conditions have been derived using different continuum and line intensity ratios. We have derived He$^{+}$, C$^{++}$ and O$^{++}$ abundances from pure recombination lines as well as abundances from collisionally excited lines for a large number of ions of different elements. We have obtained consistent estimations of the temperature fluctuation parameter, {\ts}, using different methods. We also report the detection of deuterium Balmer lines up to D$\delta$ (M16) and to D$\gamma$ (M20) in the blue wings of the hydrogen lines, which excitation mechanism seems to be continuum fluorescence. The temperature fluctuations paradigm agree with the results obtained from optical CELs and the more uncertain ones from far IR fine structure CELs in NGC 3603, although, more observations covering the same volume of the nebula are necessary to obtain solid conclusions.Comment: 22 pages, 13 Tables, 7 Figures. Accepted for publication by MNRA

The digital transformation of work: a relational view

Conversation about the current and potential effects of digital technologies on the nature of work is raging within scholarly and practitioner communities. Artificial intelligence, robotics, data analytics, digital platforms, and automation, among other technologies, are prompting a swift and profound transformation of work. Building on Pierpaolo Donati''s relational sociology, we examine the changes these technologies are likely to bring about in work as a human relation. Despite the very real threats of unemployment, job insecurity, precariousness, and surveillance, technology may also encourage the emergence of a work culture that shifts the scales toward a relational realm rather than a transactional one. To this end, we argue that work should be understood as a social relation with four dimensions: exchange value, intrinsic extra-economic purpose, communication for reciprocal services, and correspondence with primary human needs according to use values. Understanding the digital transformation of work from this point of view requires comprehending the differentiation and integration of these four dimensions

Chloroform conversion into ethane and propane by catalytic hydrodechlorination with Pd supported on activated carbons from lignin

Conversion of chloroform (TCM) by gas-phase catalytic hydrodechlorination (HDC) has been addressed to maximize the selectivity to ethane and propane. Several own-made Pd (1 wt%) catalysts have been tested. The catalysts were prepared by incipient wetness impregnation of five different activated carbons. These carbons were obtained by chemical activation of lignin with different activating agents, namely, H3PO4, ZnCl2, FeCl3, NaOH and KOH. The catalysts were fully characterized by N2 adsorption–desorption at −196 °C, CO2 adsorption at 0 °C, TPR, NH3-TPD, XRD, XPS and TEM. The activating agents provided important differences in the characteristics of activated carbon supports, and hence in the resulting catalysts, in terms of their porous texture, surface acidity, Pd oxidation state and Pd particle size distribution. NaOH and KOH activation led to carbons with the highest surface areas (2158 and 2991 m2 g−1 , respectively) and low Pd0 / Pdn+ ratios, while ZnCl2- and H3PO4-activated carbons yielded the highest surface acidity and mean Pd particle sizes. The analysis of the TOF values revealed that the HDC of TCM on these catalysts is a structure-sensitive reaction, increasing TOF values with Pd particle size. The best results, in terms of selectivity to ethane and propane, were obtained with the catalysts supported on KOH- and NaOH-activated carbons. The former allowed 80% selectivity to the target compounds at almost complete dechlorination (>99%) at 300 °C. The KOH-based catalyst showed fairly good stability at a reaction temperature of 200 °CThe authors gratefully acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) through the project CTM 2014-5300

Platinum and N-doped carbon nanostructures as catalysts in hydrodechlorination reactions

Novel Pt catalysts supported on undoped and N-doped (1% N, w) carbons with well interconnected and nanostructured mesoporosity (Vmesopore = 0.65 cm3 g−1, SEXT = 730 m2 g−1) were prepared and tested in the hydrodechlorination of 4-chlorophenol in water at 30–70 °C. The growth of Pt nanoparticles was achieved using incipient wetness impregnation and a modified colloidal synthesis. Total conversion of 4chlorophenol and 100% selectivity to cyclohexanol was achieved. The remarkable activity in the hydrogenation of the phenol resulting from hydrodechlorination has not been reported before with Pt catalysts and it is of high interest because it maximizes detoxification. When the Pt NPs were synthesized by incipient wetness impregnation some influence of the N-doping of the support was observed in the size and electronic state of the NPs. However, highly reproducible Pt NPs were prepared by in situ colloidal synthesis regardless the nature of the support. In this last case similar activity was observed for the catalysts with undoped and N-doped carbon support, although the activity increased more with temperature for the later. Apparent activation energies of 15–25 kJ mol−1 were obtained for the disappearance of 4-chlorophenolThe authors also thank to Hexion Speciality Chemicals Iberica S.A. for providing the resol resin Bakelite®PF9934 FL. The authors thank financial support (CTQ2012-32821, CTQ2015-65491_R) and C. Ruiz-García for PhD grant (BES-2013-066085) to MINEC

Improving the activity in hydrodechlorination of Pd/C catalysts by nitrogen doping of activated carbon supports

Aqueous phase 4-chlorophenol hydrodechlorination reaction was used to study the effect of N-doping of activated carbon support on the catalytic activity of Pd catalysts. Activated carbon was doped using pyridine and 1,10-phenantroline, reaching nitrogen contents of 0.42-1.22 and 1.35-4.19 % (w), respectively. All catalysts (0.75 % Pd w, carbon basis) showed relatively large Pd nanoparticles (35-55nm), but they exhibited fast and complete 4-chlorophenol disappearance in batch experiments. In runs at 30°C 4-chlorophenol disappearance was mainly ascribed to hydrodechlorination, although N-doping of the support also increased adsorption. Catalysts with supports doped with pyridine yielded higher 4-chlorophenol disappearance rate in spite of lower bulk nitrogen content, however they showed higher concentration of nitrogen species at the external surface and lower loss of surface area during the doping. 4-chlorophenol disappearance rate was boosted at 60°C, with minor differences between catalysts with undoped and N-doped supports, but generation of cyclohexanone was only observed for the ones with doped support. Phenol generation simultaneous to 4-chlorophenol disappearance was observed with all the catalysts. However, subsequent hydrogenation to cyclohexanone ocurred only with the catalysts supported on N-doped activated carbonThe authors greatly appreciate the financial support of this research from the Spanish Ministry of Economy and Competitiveness through the project CTQ2012-3282

Fossil Groups Origins III. Characterization of the sample and observational properties of fossil systems

(Abridged) Fossil systems are group- or cluster-sized objects whose luminosity is dominated by a very massive central galaxy. In the current cold dark matter scenario, these objects formed hierarchically at an early epoch of the Universe and then slowly evolved until present day. That is the reason why they are called {\it fossils}. We started an extensive observational program to characterize a sample of 34 fossil group candidates spanning a broad range of physical properties. Deep $r-$band images were taken for each candidate and optical spectroscopic observations were obtained for $\sim$ 1200 galaxies. This new dataset was completed with SDSS DR7 archival data to obtain robust cluster membership and global properties of each fossil group candidate. For each system, we recomputed the magnitude gaps between the two brightest galaxies ($\Delta m_{12}$) and the first and fourth ranked galaxies ($\Delta m_{14}$) within 0.5 $R_{{\rm 200}}$. We consider fossil systems those with $\Delta m_{12} \ge 2$ mag or $\Delta m_{14} \ge 2.5$ mag within the errors. We find that 15 candidates turned out to be fossil systems. Their observational properties agree with those of non-fossil systems. Both follow the same correlations, but fossils are always extreme cases. In particular, they host the brightest central galaxies and the fraction of total galaxy light enclosed in the central galaxy is larger in fossil than in non-fossil systems. Finally, we confirm the existence of genuine fossil clusters. Combining our results with others in the literature, we favor the merging scenario in which fossil systems formed due to mergers of $L^\ast$ galaxies. The large magnitude gap is a consequence of the extreme merger ratio within fossil systems and therefore it is an evolutionary effect. Moreover, we suggest that at least one candidate in our sample could represent a transitional fossil stage.Comment: 14 pages, 11 figures, accepted for publication in A&

Science with an ngVLA: Resolving the Radio Complexity of EXor and FUor-type Systems with the ngVLA

Episodic accretion may be a common occurrence in the evolution of young pre-main sequence stars and has important implications for our understanding of star and planet formation. Many fundamental aspects of what drives the accretion physics, however, are still unknown. The ngVLA will be a key tool in understanding the nature of these events. The high spatial resolution, broad spectral coverage, and unprecedented sensitivity will allow for the detailed analysis of outburst systems. The proposed frequency range of the ngVLA allows for observations of the gas, dust, and non-thermal emission from the star and disk.Comment: 8 pages, 1 figure, To be published in the ASP Monograph Series, "Science with a Next-Generation VLA", ed. E. J. Murphy (ASP, San Francisco, CA