738 research outputs found

    Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

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    Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome

    HCN Dimers to HCN Tetramers: Computational Exploration of Binary Reactions

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    This study explores the self and cross-dimerization of HCN and HNC dimers, key elements in prebiotic chemistry, to explore potential phenomena crucial to the early stages of life on Earth, Titan, and other extraterrestrial environments. We utilise computational analysis to reveal various reaction products, predominantly featuring imine, nitrile, amine, and iminoamine functional groups, along with N-heterocycles like aziridines, azetenes, and triazole. Transition state search methods illuminate the mechanistic details of these reactions. Notably, we identify biomarkers such as a func- tional isomer of DAMN (D95) and imidazole derivatives (D45, D76, D79), which are potential precursors to nucleobases such as adenine, and polyimines that may serve as precursors to DNA and RNA helical structures. This study enhances our under- standing of the complex chemical pathways that may have contributed to the genesis of life’s foundational molecules in various cosmic settings

    Performance of Density Functionals and Semiempirical 3c Methods for Small Gold-Thiolate Clusters

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    Amid the surge of computational studies of gold thiolate clusters in the recent past, we present a comparison of popular density functionals (DFAs) and three-part corrected methods (3c-methods) on their performance by taking a dataset consisting 18 isomers of Aun(SCH3)m (m ≀ n =1-3) stoichiometry. We have compared the efficiency and accuracy of the DFAs and 3c-methods in geometry optimization with RI-SCS-MP2 and energies with DLPNO-CCSD(T) as reference methods. The lowest energy structure out of the largest stoichiometry from our dataset i.e., Au3(SCH3)3 is considered to evaluate the computational time for SCF and gradient. Alongside, the number of optimization steps to locate the most stable minima of Au3(SCH3)3 are compared to assess the efficiency of the methods. A comparison of relevant bond lengths with the reference geometry was made to estimate the accuracy in geometry optimization. Some methods such as LC-BLYP, ⍔B97M-D3BJ, M06-2X, and PBEh-3c are unable to locate many of the minima that are found by most of the other methods; thus, the versatility in locating various minima is also an important criterion in choosing a method for the given project. We have compared the relative energies among the isomers along every stoichiometric series and the interaction energy of the gold core with the ligands to estimate the accuracy of the methods. The dependence of basis set size and relativistic effects on energies are also compared. Some of the highlights are the following. TPSS shows accuracy, whereas mPWPW is fast with comparable accuracy. The range separated hybrid DFAs are the best choice for the relative energies of the clusters. CAM-B3LYP excels, whereas B3LYP shows poor performance. Overall, LC-BLYP is a balanced performer considering both the geometry and relative stability of the structures, but it lacks diversity. The 3c-methods, although fast, are less impressive in relative stability

    Nanoclusters and Nanoalloys of Group 13 elements B, Al, and Ga: Benchmark, structure, and property analysis

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    We present a benchmark study considering AEPA16 dataset comprising atomization energy for boron group clusters. This dataset covers 46 different methods from the different range of density functionals and post HF, where MRACPF is considered as the reference. The performance of basis set is analyzed by comparing the atomization energy with the CCSD(T)\CBS results. None of the GGA and meta-GGA are accurate and the popular PBE shows maximum error among the all methods, whereas B3LYP has moderate performance. M06 and RSHX DFAs have good performance among all the DFAs. NEVPT2 is the most accurate among all the methods considered followed by coupled cluster methods, i.e., CCSD(T) and DLPNO-CCSD(T), indicating the importance of perturbative correction. All the basis with M06 show promising results (absolute error \textless 1 \kmol) with respect to the CCSD(T)\CBS. From the cost -- accuracy investigation, def2-SVP is recommended in our study as it is the fastest. Hence, we have recommended M06/def2-SVP for boron group clusters. Furthermore, we have explored the structural progress of global and local minima of pure, binary, and ternary of boron group clusters up to size 12. One characteristic feature is that Ga clusters have more rectangular faces, whereas B and Al clusters have mostly trigonal units in pure cluster\u27s form. We have got core-shell like structures, where, B makes core structure with both the Al and Ga atoms; however, Ga favors the outer position in the binary clusters. This behavior confirms the higher cohesive nature of B as compared to the Al and Ga atoms. The most favorable cluster is obtained with the maximum cluster size (12) with the equal composition of Al and Ga atoms for binary clusters. From the BE and ME of ternary clusters, we have obtained 16.67-40% B, 16.67-60% Al, and 20-50% Ga composition are favorable for the relatively stable ternary clusters as it shows negative ME

    BAl4Mg−/0/+: Global Minima with a Planar Tetracoordinate or Hypercoordinate Boron Atom

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    We have explored the chemical space of BAl4Mg−/0/+ for the first time and theoretically characterized several isomers with interesting bonding patterns. We have used chemical intuition and a cluster building method based on the tabu-search algorithm implemented in the Python program for aggregation and reaction (PyAR) to obtain the maximum number of possible stationary points. The global minimum geometries for the anion (1a) and cation (1c) contain a planar tetracoordinate boron (ptB) atom, whereas the global minimum geometry for the neutral (1n) exhibits a planar pentacoordinate boron (ppB) atom. The low-lying isomers of the anion (2a) and cation (3c) also contain a ppB atom. The low-lying isomer of the neutral (2n) exhibits a ptB atom. Ab initio molecular dynamics simulations carried out at 298 K for 2000 fs suggest that all isomers are kinetically stable, except the cation 3c. Simulations carried out at low temperatures (100 and 200 K) for 2000 fs predict that even 3c is kinetically stable, which contains a ppB atom. Various bonding analyses (NBO, AdNDP, AIM, etc.) are carried out for these six different geometries of BAl4Mg−/0/+ to understand the bonding patterns. Based on these results, we conclude that ptB/ppB scenarios are prevalent in these systems. Compared to the carbon counter-part, CAl4Mg−, here the anion (BAl4Mg−) obeys the 18 valence electron rule, as B has one electron fewer than C. However, the neutral and cation species break the rule with 17 and 16 valence electrons, respectively. The electron affinity (EA) of BAl4Mg is slightly higher (2.15 eV) than the electron affinity of CAl4Mg (2.05 eV). Based on the EA value, it is believed that these molecules can be identified in the gas phase. All the ptB/ppB isomers exhibit π/σ double aromaticity. Energy decomposition analysis predicts that the interaction between BAl4−/0/+ and Mg is ionic in all these six systems

    BAl<sub>4</sub>Mg<sup>−/0/+</sup>: Global Minima with a Planar Tetracoordinate or Hypercoordinate Boron Atom

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    We have explored the chemical space of BAl4Mg−/0/+ for the first time and theoretically characterized several isomers with interesting bonding patterns. We have used chemical intuition and a cluster building method based on the tabu-search algorithm implemented in the Python program for aggregation and reaction (PyAR) to obtain the maximum number of possible stationary points. The global minimum geometries for the anion (1a) and cation (1c) contain a planar tetracoordinate boron (ptB) atom, whereas the global minimum geometry for the neutral (1n) exhibits a planar pentacoordinate boron (ppB) atom. The low-lying isomers of the anion (2a) and cation (3c) also contain a ppB atom. The low-lying isomer of the neutral (2n) exhibits a ptB atom. Ab initio molecular dynamics simulations carried out at 298 K for 2000 fs suggest that all isomers are kinetically stable, except the cation 3c. Simulations carried out at low temperatures (100 and 200 K) for 2000 fs predict that even 3c is kinetically stable, which contains a ppB atom. Various bonding analyses (NBO, AdNDP, AIM, etc.) are carried out for these six different geometries of BAl4Mg−/0/+ to understand the bonding patterns. Based on these results, we conclude that ptB/ppB scenarios are prevalent in these systems. Compared to the carbon counter-part, CAl4Mg−, here the anion (BAl4Mg−) obeys the 18 valence electron rule, as B has one electron fewer than C. However, the neutral and cation species break the rule with 17 and 16 valence electrons, respectively. The electron affinity (EA) of BAl4Mg is slightly higher (2.15 eV) than the electron affinity of CAl4Mg (2.05 eV). Based on the EA value, it is believed that these molecules can be identified in the gas phase. All the ptB/ppB isomers exhibit π/σ double aromaticity. Energy decomposition analysis predicts that the interaction between BAl4−/0/+ and Mg is ionic in all these six systems

    CAl4Mg0/−: Global Minima with a Planar Tetracoordinate Carbon Atom

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    Isomers of CAl4Mg and CAl4Mg− have been theoretically characterized for the first time. The most stable isomer for both the neutral and anion contain a planar tetracoordinate carbon (ptC) atom. Unlike the isovalent CAl4Be case, which contains a planar pentacoordinate carbon atom as the global minimum geometry, replacing beryllium with magnesium makes the ptC isomer the global minimum due to increased ionic radii of magnesium. However, it is relatively easier to conduct experimental studies for CAl4Mg0/− as beryllium is toxic. While the neutral molecule containing the ptC atom follows the 18 valence electron rule, the anion breaks the rule with 19 valence electrons. The electron affinity of CAl4Mg is in the range of 1.96–2.05 eV. Both the global minima exhibit π/σ double aromaticity. Ab initio molecular dynamics simulations were carried out for both the global minima at 298 K for 10 ps to confirm their kinetic stability

    Multiplicity dependence of light (anti-)nuclei production in p–Pb collisions at sNN=5.02 TeV

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    The measurement of the deuteron and anti-deuteron production in the rapidity range −1 < y < 0 as a function of transverse momentum and event multiplicity in p–Pb collisions at √sNN = 5.02 TeV is presented. (Anti-)deuterons are identified via their specific energy loss dE/dx and via their time-of- flight. Their production in p–Pb collisions is compared to pp and Pb–Pb collisions and is discussed within the context of thermal and coalescence models. The ratio of integrated yields of deuterons to protons (d/p) shows a significant increase as a function of the charged-particle multiplicity of the event starting from values similar to those observed in pp collisions at low multiplicities and approaching those observed in Pb–Pb collisions at high multiplicities. The mean transverse particle momenta are extracted from the deuteron spectra and the values are similar to those obtained for p and particles. Thus, deuteron spectra do not follow mass ordering. This behaviour is in contrast to the trend observed for non-composite particles in p–Pb collisions. In addition, the production of the rare 3He and 3He nuclei has been studied. The spectrum corresponding to all non-single diffractive p-Pb collisions is obtained in the rapidity window −1 < y < 0 and the pT-integrated yield dN/dy is extracted. It is found that the yields of protons, deuterons, and 3He, normalised by the spin degeneracy factor, follow an exponential decrease with mass number

    Measurement of inclusive J/ψ\psi pair production cross section in pp collisions at s=13\sqrt{s} = 13 TeV

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    International audienceThe production cross section of inclusive J/ψ\psi pairs in pp collisions at a centre-of-mass energy s=13\sqrt{s} = 13 TeV is measured with ALICE. The measurement is performed for J/ψ\psi in the rapidity interval 2.502.5 0. The production cross section of inclusive J/ψ\psi pairs is reported to be 10.3±2.3(stat.)±1.3(syst.)10.3 \pm 2.3 {\rm (stat.)} \pm 1.3 {\rm (syst.)} nb in this kinematic interval. The contribution from non-prompt J/ψ\psi (i.e. originated from beauty-hadron decays) to the inclusive sample is evaluated. The results are discussed and compared with data
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