Assessment of Functionals for First-Principle Studies of the Structural and Electronic Properties of -Bi2O3

Fully relativistic full-potential density functional calculations with an all-electron linearized augmented plane waves plus local orbitals method were carried out to perform a comparative study on the structural and electronic properties of the cubic oxide -Bi2O3 phase, which is considered as one of the most promising materials in a variety of applications including fuel cells, sensors, and catalysts. Three different density functionals were used in our calculations, LDA, the GGA scheme in the parametrization of Perdew, Burke, and Ernzerhof (PBE96), and the hybrid scheme of Perdew-Wang B3PW91. The examined properties include lattice parameter, band structure and density of states, and charge density profiles. For this modification the three functionals reveal the characteristics of a metal and the existence of minigaps at high symmetry points of the band structure when spin-orbit coupling is taken into account. Density of states exhibits hybridization of Bi 6s and O 2p orbitals and the calculated charge density profiles exhibit the ionic character in the chemical bonding of this compound. The B3PW91 hybrid functional provided a better agreement with the experimental result for the lattice parameter, revealing the importance of Hartree-Fock exchange in this compound

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Synergetic effect in RuxMo(1-x)S2/SBA-15 hydrodesulfurization catalysts: Comparative experimental and DFT studies

The effect of introducing Ru impurities into the MoS2crystalline structure of the sulfided RuxMo(1-x)S2/SBA-15catalysts have been investigated using density functional theory (DFT) calculations and the catalyst character-ization by different techniques (chemical analysis (ICP-AES), temperature-programmed reduction (TPR), X-raydiffraction (XRD), N2physisorption, DRIFTS of adsorbed pyridine (DRIFTS-Py) and X-ray photoelectron spec-troscopy (XPS)). The catalyst activity was tested in the hydrodesulfurization (HDS) of dibenzothiophene (DBT)reaction carried out in a batch reactor,T= 320 °C and total H2pressure of 5.5 MPa. From electronic structureDFT calculations is was concluded that the 4d orbitals of both Mo and Ru played an important role in the catalystoptimization being the processes of transport and charge transference the most important ones. It was found thatthe enrichment with Ru, promotes a greater electronic participation (DOS at the Fermi level) of the differentatoms in the RuxMo(1-x)S2phase leading to metallization of the Mo ions. The catalyst activity in HDS of DBTreaction demonstrated a similar behavior to that of theoretical density of states (DOS) calculated via DFT. Allbimetallic systems presented the synergetic effect between Ru and Mo in the HDS of DBT reaction overRuxMo(1-x)S2/SBA-15 catalysts. The highest activity observed for Ru content ofx= 0.4 was consistent with theoretical results predicting that the optimum DOS contributions should be aroundx= 0.44. The most activeRu0.4Mo0.6S2/SBA-15 exhibit the best hydrogenation properties linked with the Ru-induced metallization of Moions in the Ru0.4Mo0.6S2phase. This catalyst showed two-fold higher hydrogenation properties than CoMoS/γ-Al2O3reference catalyst. The linear dependencies of initial activity on Brønsted-to-Lewis acidities ratio (fromDRIFT-Py) and total metal surface exposure (from XPS) were observed.The authors acknowledge the Consejo Nacional de Ciencia yTecnología (CONACyT) for the financial support of CONACYT (Projects117373 and 152012). D.H. Galvan and B. Pawelec acknowledges Supercómputo UNAM through project No. LANCAD-UNAM-DGTIC-041and CTQ2016-76505-C3-1 project supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), respectively