Selective gas phase hydrogenation of nitroarenes over Mo2C-supported Au–Pd

Open Access via RSC Gold 4 Gold Financial support to Dr. X. Wang through the Overseas Research Students Award Scheme (ORSAS) is acknowledged. Dr. N. Perret also acknowledges financial support from COST Action MP0903 Nanoalloys.Peer reviewedPublisher PD

Effect of Crystallographic Phase (β vs. γ) and Surface Area on Gas Phase Nitroarene Hydrogenation Over Mo2N and Au/Mo2N

The catalytic action of Mo2N and Au/Mo2N has been assessed in the selective gas phase hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). The nitrides were synthesised via temperature programmed treatment of MoO3 in H2+N2 and Au introduced by deposition-precipitation with urea. We have examined the influence of nitride crystallographic phase (tetragonal β-Mo2N vs. cubic γ-Mo2N) and surface area (7-66m2g−1) on the catalytic response. Catalyst activation by temperature programmed reduction has been monitored and the reduced catalysts characterised in terms of BET area/pore volume, H2 chemisorption/temperature programmed desorption (TPD), powder X-ray diffraction (XRD), elemental analysis, scanning (SEM) and transmission (TEM) electron microscopy and X-ray photoelectron spectroscopy (XPS) measurements. The formation of β- and γ-Mo2N was confirmed by XRD and TEM. γ-Mo2N exhibits a platelet morphology whereas β-Mo2N is characterised by an aggregation of small crystallites. Hydrogen chemisorption and TPD analysis have established a greater hydrogen uptake capacity (per unit area) for β-Mo2N relative to γ-Mo2N, which is associated with surface nitrogen deficiency, i.e. higher surface Mo/N for β-Mo2N. Incorporation of Au on both nitrides resulted in an increase in surface hydrogen. The Au phase takes the form of nano-scale particles with a mean size of 7 and 4nm on β-Mo2N and γ-Mo2N, respectively. Both β-Mo2N and γ-Mo2N promoted the exclusive hydrogenation of p-CNB to p-CAN where the β-form delivered a higher specific (per m2) rate; the specific rate for γ-Mo2N was independent of surface area. The inclusion of Au on both nitrides served to enhance p-CAN productio

Genetics of venous thrombosis: insights from a new genome wide association study

Background: Venous Thrombosis (VT) is a common multifactorial disease associated with a major public health burden. Genetics factors are known to contribute to the susceptibility of the disease but how many genes are involved and their contribution to VT risk still remain obscure. We aimed to identify genetic variants associated with VT risk. Methodology/Principal Findings: We conducted a genome-wide association study (GWAS) based on 551,141 SNPs genotyped in 1,542 cases and 1,110 controls. Twelve SNPs reached the genome-wide significance level of 2.0×10−8 and encompassed four known VT-associated loci, ABO, F5, F11 and FGG. By means of haplotype analyses, we also provided novel arguments in favor of a role of HIVEP1, PROCR and STAB2, three loci recently hypothesized to participate in the susceptibility to VT. However, no novel VT-associated loci came out of our GWAS. Using a recently proposed statistical methodology, we also showed that common variants could explain about 35% of the genetic variance underlying VT susceptibility among which 3% could be attributable to the main identified VT loci. This analysis additionally suggested that the common variants left to be identified are not uniformly distributed across the genome and that chromosome 20, itself, could contribute to ∼7% of the total genetic variance. Conclusions/Significance: This study might also provide a valuable source of information to expand our understanding of biological mechanisms regulating quantitative biomarkers for VT

A first update on mapping the human genetic architecture of COVID-19

peer reviewe

Growth of understorey Scots pine (Pinus sylvestris L.) saplings in response to light in mixed temperate forest

Predicting growth and mortality of trees growing in the understorey requires estimates of their light requirements but would provide valuable help for the management of irregular forest stands, especially for light-demanding species like Scots pine (Pinus sylvestris L.). Sixty-five pine saplings from 0.4 to 6 m high and aged from 2 to 58 years were sampled in different light conditions in the understorey of mixed sessile oak-Scots pine stands in a temperate forest in central France. Each pine sapling was described by its height, diameter and age and by the light reaching its apex. Pine sapling height and diameter were positively correlated with light and age. The results highlighted that Scots pine, a tree species usually described as shade-intolerant, is able to grow, although slowly, in shaded conditions (less than 10 per cent of full sunlight). However, the results also showed that a more shaded growing environment leads to lower maximal pine sapling height whatever its age. Together with results from studies on other species, these results provide further evidence of a critical sapling size at a given light level beyond which the pine sapling is likely to die and suggest that this critical size increases with light availability

Growth of understorey Scots pine (Pinus sylvestris L.) saplings in response to light in mixed temperate forest

Predicting growth and mortality of trees growing in the understorey requires estimates of their light requirements but would provide valuable help for the management of irregular forest stands, especially for light-demanding species like Scots pine (Pinus sylvestris L.). Sixty-five pine saplings from 0.4 to 6 m high and aged from 2 to 58 years were sampled in different light conditions in the understorey of mixed sessile oak-Scots pine stands in a temperate forest in central France. Each pine sapling was described by its height, diameter and age and by the light reaching its apex. Pine sapling height and diameter were positively correlated with light and age. The results highlighted that Scots pine, a tree species usually described as shade-intolerant, is able to grow, although slowly, in shaded conditions (less than 10 per cent of full sunlight). However, the results also showed that a more shaded growing environment leads to lower maximal pine sapling height whatever its age. Together with results from studies on other species, these results provide further evidence of a critical sapling size at a given light level beyond which the pine sapling is likely to die and suggest that this critical size increases with light availability

Synthesis and characterization of binary and ternary nitride nanoparticles for ammonia synthesis

National audienc

Activity of heterogeneous supported Cu and Ru catalysts in acceptor-less alcohol dehydrogenation

International audienceAcceptor-less alcohol dehydrogenation reaction allows the co-production of added-value carbonyl compounds and H 2 from alcohols. Focusing on supported Ru and Cu catalysts, we evaluated the support effect on the dehydrogenation of 2-octanol and 1-octanol and identified the side products as resulting from aldolisation coupling. The most active and selective catalysts were then tested on the aliphatic vicinal-diol octan-1,2-diol and the highest conversion was reached using Cu/ZrO 2 (60%) with a high selectivity (94%) towards 1-hydroxy-2-octanone

Xylitol Hydrogenolysis over Ruthenium-Based Catalysts: Effect of Alkaline Promoters and Basic Oxide-Modified Catalysts

International audienceThe aqueous-phase hydrogenolysis of xylitol into glycols over Ru/C was performed in the presence and absence of a wide range of concentrations of Ca(OH)2 to investigate the reaction pathway. Without base, epimerization and cascade decarbonylation were the predominant reactions with high selectivities to C5 and C4 alditols and light alkanes at full conversion. Glycol production was obtained by the addition of Ca(OH)2 to promote the retro-aldol reaction. It competed with reactions without base and became the main reaction for a OH−/ xylitol molar ratio Rmol(OH/xylitol) of 0.13, and high selectivities to glycols (56 %) and glycerol (16 %) were observed. However, lactate was a byproduct at up to 27 % with a high base amount (Rmol(OH/xylitol)=0.68). Bifunctional Ru/metal oxide/C catalysts (metal: Zn, Sn, Mn, Sr, W) were synthesized and were able to cleave the C−C bond into glycols without a base promoter. The 3.1 wt %Ru/MnO(4.5 %)/C catalyst was the most active (220 h−1) with reasonable selectivity to glycols (22 %) and glycerol (10 %) and a low production of lactate (<1 %). Nevertheless, metal oxide leaching of the catalyst was observed likely because of the production of traces of lactate

Ru-(Mn-M)OX Solid Base Catalysts for the Upgrading of Xylitol to Glycols in Water

A series of Ru-(Mn-M)OX catalysts (M: Al, Ti, Zr, Zn) prepared by co-precipitation were investigated in the hydrogenolysis of xylitol in water to ethylene glycol, propylene glycol and glycerol at 200 &deg;C and 60 bar of H2. The catalyst promoted with Al, Ru-(Mn-Al)OX, showed superior activity (57 h&minus;1) and a high global selectivity to glycols and glycerol of 58% at 80% xylitol conversion. In comparison, the catalyst prepared by loading Ru on (Mn-Al)OX, Ru/(Mn-Al)OX was more active (111 h&minus;1) but less selective (37%) than Ru-(Mn-Al)OX. Characterization of these catalysts by XRD, BET, CO2-TPD, NH3-TPD and TEM showed that Ru/(Mn-Al)OX contained highly dispersed and uniformly distributed Ru particles and fewer basic sites, which favored decarbonylation, epimerization and cascade decarbonylation reactions instead of retro-aldol reactions producing glycols. The hydrothermal stability of Ru-(Mn-Al)OX was improved by decreasing the xylitol/catalyst ratio, which decreased the formation of carboxylic acids and enabled recycling of the catalyst, with a very low deactivation