Origin of Low Thermal Conductivity in Nuclear Fuels

Using a novel many-body approach, we report lattice dynamical properties of UO2 and PuO2 and uncover various contributions to their thermal conductivities. Via calculated Grueneisen constants, we show that only longitudinal acoustic modes having large phonon group velocities are efficient heat carriers. Despite the fact that some optical modes also show their velocities which are extremely large, they do not participate in the heat transfer due to their unusual anharmonicity. Ways to improve thermal conductivity in these materials are discussed.Comment: 4 pages, 3 figures, 1 tabl

Computational Screening of Repurposed Drugs Targeting Sars-Cov-2 Main Protease By Molecular Docking

Background: COVID-19 (Coronavirus disease 2019) is caused by the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), which poses significant global health and economic crisis that urges effective treatment. Methods: A total of 11 molecules (baricitinib, danoprevir, dexamethasone, hydroxychloroquine, ivermectin, lopinavir, methylprednisolone, remdesivir, ritonavir and saridegib, ascorbic acid, and cepharanthine) were selected for molecular docking studies using AutoDock VINA to study their antiviral activities via targeting SARS-CoV’s main protease (Mpro), a cysteine protease that mediates the maturation cleavage of polyproteins during virus replication. Results: Three drugs showed stronger binding affinity toward Mpro than N3 (active Mpro inhibitor as control): danoprevir (–7.7 kcal/mol), remdesivir (–8.1 kcal/mol), and saridegib (–7.8 kcal/mol). Two primary conventional hydrogen bonds were identified in the danoprevir-Mpro complex at GlyA:143 and GlnA:189, whereas the residue GluA:166 formed a carbon–hydrogen bond. Seven main conventional hydrogen bonds were identified in the remdesivir at AsnA:142, SerA:144, CysA:145, HisA:163, GluA:166, and GlnA:189, whereas two carbon–hydrogen bonds were formed by the residues HisA:41 and MetA:165. Cepharanthine showed a better binding affinity toward Mpro (–7.9 kcal/mol) than ascorbic acid (–5.4 kcal/mol). Four carbon–hydrogen bonds were formed in the cepharanthine-Mpro complex at HisA:164, ProA;168, GlnA;189, and ThrA:190. Conclusion: The findings of this study propose that these drugs are potentially inhibiting the SAR-CoV-2 virus by targeting the Mpro protein

Antimicrobial peptide identification using multi-scale convolutional network

Background: Antibiotic resistance has become an increasingly serious problem in the past decades. As an alternative choice, antimicrobial peptides (AMPs) have attracted lots of attention. To identify new AMPs, machine learning methods have been commonly used. More recently, some deep learning methods have also been applied to this problem. Results: In this paper, we designed a deep learning model to identify AMP sequences. We employed the embedding layer and the multi-scale convolutional network in our model. The multi-scale convolutional network, which contains multiple convolutional layers of varying filter lengths, could utilize all latent features captured by the multiple convolutional layers. To further improve the performance, we also incorporated additional information into the designed model and proposed a fusion model. Results showed that our model outperforms the state-of-the-art models on two AMP datasets and the Antimicrobial Peptide Database (APD)3 benchmark dataset. The fusion model also outperforms the state-of-the-art model on an anti-inflammatory peptides (AIPs) dataset at the accuracy. Conclusions: Multi-scale convolutional network is a novel addition to existing deep neural network (DNN) models. The proposed DNN model and the modified fusion model outperform the state-of-the-art models for new AMP discovery. The source code and data are available at https://github.com/zhanglabNKU/APIN

3-Phenyl­tetra­hydro­furan-2,5-dione

In the title compound, C10H8O3, the dihedral angle between the approximately planar tetra­hydro­furan-2,5-dione ring [maximum deviation 0.014 (3) Å] and the phenyl ring is 85.68 (8)°. Weak C—H⋯O=C inter­molecular hydrogen-bonding contacts are observed in the structure

Calculations of Magnetic Exchange Interactions in Mott--Hubbard Systems

An efficient method to compute magnetic exchange interactions in systems with strong correlations is introduced. It is based on a magnetic force theorem which evaluates linear response due to rotations of magnetic moments and uses a novel spectral density functional framework combining our exact diagonalization based dynamical mean field and local density functional theories. Applications to spin waves and magnetic transition temperatures of 3d metal mono--oxides as well as high--T_{c} superconductors are in good agreement with experiment

Bis(5-bromo­pyridine-2-carboxyl­ato-κO)triphenyl­anti­mony(V)

In the title compound, [Sb(C6H5)3(C6H3BrNO2)2], the Sb center has a distorted trigonal–bipyramidal geometry, with two carboxyl­ate O atoms of two 5-bromo­pyridine-2-carboxyl­ate ligands in equatorial positions and three phenyl ligands in axial positions. The crystal structure is stabilized by C—H⋯Br hydrogen bonds and inter­molecular C—Br⋯π inter­actions [C⋯π = 3.57 (1) Å]

A new genus and a new species of the tribe Haplotropidini Sergeev (Orthoptera: Acridoidea, Pamphagidae, Pamphaginae) with a key to the three genera of the tribe from China

This paper reports a new genus and a species of the tribe Haplotropidini Sergeev, 1995, i.e. Sulcohumpacris Yin, Yin et Cao gen. n. and Sulcohumpacris hebeiensis Yin, Yin et Cao sp. n. from Hebei Province, China. The new genus is similar to Humphaplotropis Xiao, Yin et Yin, 2013, but differs from the latter by the hump-formed pronotum along the median keel being deeply cut by hind sulcus and hence divided in two waves in lateral view, the anterior margin being acutely angular in the middle, the apex not reaching the hindmargin of the eyes, the frontal ridge being widened at the median ocellus, and the abdomen having large teeth along the median keel in lateral view. A key to the three genera of this Chinese tribe is given. The type specimens are deposited in the Museum of Hebei University, Baoding, China

Anisotropy, Itineracy, and Magnetic Frustration in High-Tc Iron Pnictides

Using first-principle density functional theory calculations combined with insight from a tight-binding representation, dynamical mean field theory, and linear response theory, we have extensively investigated the electronic structures and magnetic interactions of nine ferropnictides representing three different structural classes. The calculated magnetic interactions are found to be short-range, and the nearest ($J_{1a}$) and next-nearest ($J_{2}$) exchange constants follow the universal trend of J_{1a}/2J_{2}\sim 1, despite their itinerant origin and extreme sensitivity to the z-position of As. These results bear on the discussion of itineracy versus magnetic frustration as the key factor in stabilizing the superconducting ground state. The calculated spin wave dispersions show strong magnetic anisotropy in the Fe plane, in contrast to cuprates.Comment: Fig.4 updated: Phys. Rev. Lett (in press