The effect of Mg location on Co-Mg-Ru/gamma-Al2O3 Fischer-Tropsch catalysts

The effectiveness of Mg as a promoter of Co-Ru/γ-Al(2)O(3) Fischer–Tropsch catalysts depends on how and when the Mg is added. When the Mg is impregnated into the support before the Co and Ru addition, some Mg is incorporated into the support in the form of Mg(x)Al(2)O(3+x) if the material is calcined at 550°C or 800°C after the impregnation, while the remainder is present as amorphous MgO/MgCO(3) phases. After subsequent Co-Ru impregnation Mg(x)Co(3−x)O(4) is formed which decomposes on reduction, leading to Co(0) particles intimately mixed with Mg, as shown by high-resolution transmission electron microscopy. The process of impregnating Co into an Mg-modified support results in dissolution of the amorphous Mg, and it is this Mg which is then incorporated into Mg(x)Co(3−x)O(4). Acid washing or higher temperature calcination after Mg impregnation can remove most of this amorphous Mg, resulting in lower values of x in Mg(x)Co(3−x)O(4). Catalytic testing of these materials reveals that Mg incorporation into the Co oxide phase is severely detrimental to the site-time yield, while Mg incorporation into the support may provide some enhancement of activity at high temperature

\u3cem\u3eHerschel\u3c/em\u3e Observations of Extended Atomic Gas in the Core of the Perseus Cluster

We present Herschel observations of the core of the Perseus cluster of galaxies. Especially intriguing is the network of filaments that surround the brightest cluster galaxy, NGC 1275, previously imaged extensively in Hα and CO. In this work, we report detections of far-infrared (FIR) lines, in particular, [C II] 158, [O I] 63, [N II] 122, [O IB] 145 and [O III] 88  μm, withHerschel. All lines are spatially extended, except [O III], with the [C II] line emission extending up to 25 kpc from the core. [C II] emission is found to be co-spatial with Hα and CO. Furthermore, [C II] shows a similar velocity distribution to CO, which has been shown in previous studies to display a close association with the Hα kinematics. The spatial and kinematical correlation among [C II], Hα and CO gives us confidence to model the different components of the gas with a common heating model. With the help of FIR continuum Herschel measurements, together with a suite of coeval radio, sub-millimetre and IR data from other observatories, we performed a spectral energy distribution fitting of NGC 1275 using a model that contains contributions from dust emission as well as synchrotron active galactic nucleus emission. This has allowed us to accurately estimate the dust parameters. The data indicate a low dust emissivity index, β ≈ 1, a total dust mass close to 107 M⊙, a cold dust component with temperature 38 ± 2 K and a warm dust component with temperature 116 ± 9 K. The FIR-derived star formation rate is 24 ± 1 M⊙ yr−1, which is in agreement with the far-ultraviolet-derived star formation rate in the core, determined after applying corrections for both Galactic and internal reddening. The total IR luminosity in the range 8–1000  μm is inferred to be 1.5 × 1011 L⊙, making NGC 1275 a luminous IR galaxy. We investigated in detail the source of the Herschel FIR and Hα emissions emerging from a core region 4 kpc in radius. Based on simulations conducted using the radiative transfer code, CLOUDY, a heating model comprising old and young stellar populations is sufficient to explain these observations. The optical line ratios indicate that there may be a need for a second heating component. However, stellar photoionization seems to be the dominant mechanism. We have also detected [C II] in three well-studied regions of the filaments.Herschel, with its superior sensitivity to FIR emission, can detect far colder atomic gas than previous studies. We find an [O I]/[C II] ratio about 1 dex smaller than predicted by the otherwise functional Ferland (2009) model. That study considered optically thin emission from a small cell of gas and by design did not consider the effects of reasonable column densities. The line ratio suggests that the lines are optically thick, as is typical of galactic photodissociation regions, and implies that there is a large reservoir of cold atomic gas. This was not included in previous inventories of the filament mass and may represent a significant component

\u3cem\u3eHerschel\u3c/em\u3e Observations of the Centaurus Oluster - the Dynamics of Cold Gas in a Cool Core

Brightest cluster galaxies (BCGs) in the cores of galaxy clusters have distinctly different properties from other low-redshift massive ellipticals. The majority of the BCGs in cool-core clusters show signs of active star formation. We present observations of NGC 4696, the BCG of the Centaurus galaxy cluster, at far-infrared (FIR) wavelengths with theHerschel space telescope. Using the PACS spectrometer, we detect the two strongest coolants of the interstellar medium, [C II] at 157.74 μm and [O I] at 63.18 μm, and in addition [N II] at 121.90 μm. The [C II] emission is extended over a region of 7 kpc with a similar spatial morphology and kinematics to the optical Hα emission. This has the profound implication that the optical hydrogen recombination line, Hα, the optical forbidden lines, [N II] λ6583 Å, the soft X-ray filaments and the FIR [C II] line all have the same energy source. We also detect dust emission using the PACS and SPIRE photometers at all six wavebands. We perform a detailed spectral energy distribution fitting using a two-component modified blackbody function and find a cold 19-K dust component with mass 1.6 × 106 M⊙ and a warm 46-K dust component with mass 4.0 × 103 M⊙. The total FIR luminosity between 8 and 1000 μm is 7.5 × 108 L⊙, which using Kennicutt relation yields a low star formation rate of 0.13 M⊙ yr−1. This value is consistent with values derived from other tracers, such as ultraviolet emission. Combining the spectroscopic and photometric results together with optical Hα, we model emitting clouds consisting of photodissociation regions adjacent to ionized regions. We show that in addition to old and young stellar populations, there is another source of energy, such as cosmic rays, shocks or reconnection diffusion, required to excite the Hα and [C II] filaments

Novel cobalt zinc oxide Fischer-Tropsch catalysts synthesised using supercritical anti-solvent precipitation

Cobalt zinc oxide catalysts have been prepared by anti-solvent precipitation in supercritical CO2 and investigated for CO hydrogenation. Here we show how the textural and catalytic properties of the catalyst can be tailored by the addition of water to the initial solution of cobalt and zinc acetates in methanol. Characterization of the catalysts by powder X-ray diffraction, infra-red and Raman spectroscopy showed that in the absence of water a high surface area mixed acetate was produced which upon calcination formed wurtzite type Zn1−xCoxO and spinel type ZnxCo3−xO4. The addition of 5 vol.% water resulted in a phase separated Co3O4/ZnO catalyst and enhanced active cobalt surface area as a result of disruption of the solvent/CO2 phase equilibrium during precipitation

\u3cem\u3eHST\u3c/em\u3e Imaging of the Dusty Filaments and Nucleus Swirl in NGC4696 at the Centre of the Centaurus Cluster

Narrow-band HST imaging has resolved the detailed internal structure of the 10 kpc diameter H α+[N II] emission line nebulosity in NGC4696, the central galaxy in the nearby Centaurus cluster, showing that the dusty, molecular, filaments have a width of about 60 pc. Optical morphology and velocity measurements indicate that the filaments are dragged out by the bubbling action of the radio source as part of the active galactic nucleus feedback cycle. Using the drag force we find that the magnetic field in the filaments is in approximate pressure equipartition with the hot gas. The filamentary nature of the cold gas continues inwards, swirling around and within the Bondi accretion radius of the central black hole, revealing the magnetic nature of the gas flows in massive elliptical galaxies. HST imaging resolves the magnetic, dusty, molecular filaments at the centre of the Centaurus cluster to a swirl around and within the Bondi radius

\u3cem\u3eHerschel\u3c/em\u3e Photometry of Brightest Cluster Galaxies in Cooling Flow Clusters

The dust destruction timescales in the cores of clusters of galaxies are relatively short given their high central gas densities. However, substantial mid-infrared and sub-mm emission has been detected in many brightest cluster galaxies. In this letter we present Herschel PACS and SPIRE photometry of the brightest cluster galaxy in three strong cooling flow clusters, A1068, A2597 and Zw3146. This photometry indicates that a substantial mass of cold dust is present (\u3e 3×107 M⊙) at temperatures significantly lower (20–28 K) than previously thought based on limited MIR and/or sub-mm results. The mass and temperature of the dust appear to match those of the cold gas traced by CO with a gas-to-dust ratio of 80–120

\u3cem\u3eHerschel\u3c/em\u3e Observations of FIR Emission Lines in Brightest Cluster Galaxies

The question of how much gas cools in the cores of clusters of galaxies has been the focus of many, multiwavelength studies in the past 30 years. In this letter we present the first detections of the strongest atomic cooling lines, [Cii], [Oi] and [Nii] in two strong cooling flow clusters, A1068 and A2597, using Herschel-PACS. These spectra indicate that the substantial mass of cold molecular gas (\u3e 109 M⊙) known to be present in these systems is being irradiated by intense UV radiation, most probably from young stars. The line widths of these FIR lines indicate that they share dynamics similar but not identical to other ionised and molecular gas traced by optical, near-infrared and CO lines. The relative brightness of the FIR lines compared to CO and FIR luminosity is consistent with other star-forming galaxies indicating that the properties of the molecular gas clouds in cluster cores and the stars they form are not unusual. These results provide additional evidence for a reservoir of cold gas that is fed by the cooling of gas in the cores of the most compact clusters and provide important diagnostics of the temperature and density of the dense clouds this gas resides in

The Post-Shock Chemical Lifetimes of Outflow Tracers and a Possible New Mechanism to Produce Water Ice Mantles

We have used a coupled time-dependent chemical and dynamical model to investigate the lifetime of the chemical legacy left in the wake of C-type shocks. We concentrate this study on the chemistry of H2O and O2, two molecules which are predicted to have abundances that are significantly affected in shock-heated gas. Two models are presented: (1) a three-stage model of pre-shock, shocked, and post-shock gas; and (2) a Monte-Carlo cloud simulation where we explore the effects of stochastic shock activity on molecular gas over a cloud lifetime. In agreement with previous studies, we find that shock velocities in excess of 10 km s^-1 are required to convert all of the oxygen not locked in CO into H2O before the gas has an opportunity to cool. For pure gas-phase models the lifetime of the high water abundances, or ``H2O legacy'', in the post-shock gas is 4 - 7 x 10^5 years. Through the Monte Carlo cloud simulation we demonstrate that the time-average abundance of H2O is a sensitive function of the frequency of shocks. Thus we predict that the abundance of H2O and other known outflow tracers can be used to trace the history of shock activity in molecular gas. For gas-grain models we find that the abundance of water-ice on grain surfaces can be quite large and is comparable to that observed in molecular clouds. This offers a possible alternative method to create water mantles without resorting to grain surface chemistry: gas heating and chemical modification due to a C-type shock and subsequent depletion of the gas-phase species onto grain mantles.Comment: 31 pages (including 16 figures), using aas2pp4.sty. To be published in ApJ, June 1 1998 issu

Genetic mechanisms of critical illness in COVID-19.

Host-mediated lung inflammation is present1, and drives mortality2, in the critical illness caused by coronavirus disease 2019 (COVID-19). Host genetic variants associated with critical illness may identify mechanistic targets for therapeutic development3. Here we report the results of the GenOMICC (Genetics Of Mortality In Critical Care) genome-wide association study in 2,244 critically ill patients with COVID-19 from 208 UK intensive care units. We have identified and replicated the following new genome-wide significant associations: on chromosome 12q24.13 (rs10735079, P = 1.65 × 10-8) in a gene cluster that encodes antiviral restriction enzyme activators (OAS1, OAS2 and OAS3); on chromosome 19p13.2 (rs74956615, P = 2.3 × 10-8) near the gene that encodes tyrosine kinase 2 (TYK2); on chromosome 19p13.3 (rs2109069, P = 3.98 ×  10-12) within the gene that encodes dipeptidyl peptidase 9 (DPP9); and on chromosome 21q22.1 (rs2236757, P = 4.99 × 10-8) in the interferon receptor gene IFNAR2. We identified potential targets for repurposing of licensed medications: using Mendelian randomization, we found evidence that low expression of IFNAR2, or high expression of TYK2, are associated with life-threatening disease; and transcriptome-wide association in lung tissue revealed that high expression of the monocyte-macrophage chemotactic receptor CCR2 is associated with severe COVID-19. Our results identify robust genetic signals relating to key host antiviral defence mechanisms and mediators of inflammatory organ damage in COVID-19. Both mechanisms may be amenable to targeted treatment with existing drugs. However, large-scale randomized clinical trials will be essential before any change to clinical practice

\u3cem\u3eHerschel\u3c/em\u3e Observations of Extended Atomic Gas in the Core of the Perseus Cluster

We present Herschel observations of the core of the Perseus cluster of galaxies. Especially intriguing is the network of filaments that surround the brightest cluster galaxy, NGC 1275, previously imaged extensively in Hα and CO. In this work, we report detections of far-infrared (FIR) lines, in particular, [C II] 158, [O I] 63, [N II] 122, [O IB] 145 and [O III] 88  μm, withHerschel. All lines are spatially extended, except [O III], with the [C II] line emission extending up to 25 kpc from the core. [C II] emission is found to be co-spatial with Hα and CO. Furthermore, [C II] shows a similar velocity distribution to CO, which has been shown in previous studies to display a close association with the Hα kinematics. The spatial and kinematical correlation among [C II], Hα and CO gives us confidence to model the different components of the gas with a common heating model. With the help of FIR continuum Herschel measurements, together with a suite of coeval radio, sub-millimetre and IR data from other observatories, we performed a spectral energy distribution fitting of NGC 1275 using a model that contains contributions from dust emission as well as synchrotron active galactic nucleus emission. This has allowed us to accurately estimate the dust parameters. The data indicate a low dust emissivity index, β ≈ 1, a total dust mass close to 107 M⊙, a cold dust component with temperature 38 ± 2 K and a warm dust component with temperature 116 ± 9 K. The FIR-derived star formation rate is 24 ± 1 M⊙ yr−1, which is in agreement with the far-ultraviolet-derived star formation rate in the core, determined after applying corrections for both Galactic and internal reddening. The total IR luminosity in the range 8–1000  μm is inferred to be 1.5 × 1011 L⊙, making NGC 1275 a luminous IR galaxy. We investigated in detail the source of the Herschel FIR and Hα emissions emerging from a core region 4 kpc in radius. Based on simulations conducted using the radiative transfer code, CLOUDY, a heating model comprising old and young stellar populations is sufficient to explain these observations. The optical line ratios indicate that there may be a need for a second heating component. However, stellar photoionization seems to be the dominant mechanism. We have also detected [C II] in three well-studied regions of the filaments.Herschel, with its superior sensitivity to FIR emission, can detect far colder atomic gas than previous studies. We find an [O I]/[C II] ratio about 1 dex smaller than predicted by the otherwise functional Ferland (2009) model. That study considered optically thin emission from a small cell of gas and by design did not consider the effects of reasonable column densities. The line ratio suggests that the lines are optically thick, as is typical of galactic photodissociation regions, and implies that there is a large reservoir of cold atomic gas. This was not included in previous inventories of the filament mass and may represent a significant component