On Thompson Problem

In 1987, the second author of this paper reported his conjecture, all finite simple groups $S$ can be characterized uniformly using the order of $S$ and the set of element orders in $S$, to Prof. J. G. Thompson. In their communications, Thompson posed his problem about the judgment of solvability of finite groups $G$. In this paper we give a positive answer for Thompson's problem if the prime graph of $G$ is not connection.Comment: 8 page

Microstructural Evolution in Chroming Coatings Friction Pairs under Dry Sliding Test Conditions

The microstructures of subsurface layers of 20CrMnTi steel pins against chroming and nonchroming T10 under dry sliding tests were studied by means of OM (optical microscopy), XRD (X-ray diffraction), and SEM (scanning electron microscopy). Results showed that the chroming coating strengthened the disc surface and significantly affected microstructural evolution. Three layers—the matrix, deformation layer (DL), and surface layer (SL)—formed in 20CrMnTi for the chroming T10. The matrix and deformation layer (DL) formed in 20CrMnTi for the nonchroming T10. The formation of the microstructure was considered as a result of the shear deformation

The dynamic changes of mango (Mangifera indica L.) epicuticular wax during fruit development and effect of epicuticular wax on Colletotrichum gloeosporioides invasion

Mango fruits are susceptible to diseases, such as anthracnose, during fruit development, leading to yield reduction. Epicuticular wax is closely related to resistance of plants to pathogenic bacterial invasion. In this study, the effect of mango fruit epicuticular wax on the invasion of Colletotrichum gloeosporioides was investigated, followed by to understand the changes of wax chemical composition and crystal morphology during mango fruit development using GC-MS and SEM. Results showed that the epicuticular wax of mango fruits can prevent the invasion of C. gloeosporioides, and ‘Renong’ showed the strongest resistance to C. gloeosporioides. The wax content of four mango varieties first increased and then decreased from 40 days after full bloom (DAFB) to 120 DAFB. In addition, 95 compounds were detected in the epicuticular wax of the four mango varieties at five developmental periods, in which primary alcohols, terpenoids and esters were the main wax chemical composition. Furthermore, the surface wax structure of mango fruit changed dynamically during fruit development, and irregular platelet-like crystals were the main wax structure. The present study showed the changes of wax content, chemical composition and crystal morphology during mango fruit development, and the special terpenoids (squalene, farnesyl acetate and farnesol) and dense crystal structure in the epicuticular wax of ‘Renong’ fruit may be the main reason for its stronger resistance to C. gloeosporioides than other varieties. Therefore, these results provide a reference for the follow-up study of mango fruit epicuticular wax synthesis mechanism and breeding

The OpenMolcas Web: A Community-Driven Approach to Advancing Computational Chemistry

The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in the stable branch of the package or via interfaces with other packages. These developments span a wide range of topics in computational chemistry and are presented in thematic sections: electronic structure theory, electronic spectroscopy simulations, analytic gradients and molecular structure optimizations, ab initio molecular dynamics, and other new features. This report offers an overview of the chemical phenomena and processes OpenMolcas can address, while showing that OpenMolcas is an attractive platform for state-of-the-art atomistic computer simulations

THEORETICAL STUDIES OF FUNDAMENTAL INTERACTIONS OF ACTINIDES WITH SYSTEMS CONTAINING P, D AND F BLOCK ELEMENTS

The relativistic correlation consistent basis sets for actinide elements as well as the 5d metals platinum (Pt) and gold (Au) were developed with the Douglas-Kroll-Hess 3rd order Hamiltonian, which made possible the subsequent accurate composite computational studies of thermochemical and spectroscopic properties for actinide-containing systems. A variety of gas phase investigations were taken to look into the characteristics of interactions for mainly the actinyls (actinide dioxides). Those include complexation for actinyl molecules (cations) UO22+/1+/0 and NpO22+/1+/0 with candidates from the p-block O2, N2, CO, and NO, two reactions regarding the actinide-transition metal molecules PtAnO2+/1+/0 and the cation-cation interactions (CCI) studies of the dimerization processes within the f-block monomers AnO22+/1+. The conclusions are for p-block small molecules, they can thermodynamically coordinate to the metal center of an actinyl through electron donation or acception, the electron back donating into the π* orbital of the small molecule activated the small molecules measured by calculated bond elongation and frequency red-shifts. For the d-block transition metal molecules, the reaction enthalpies calculated implied that it is thermodynamically favored for adding a Pt atom to an AnOn+ piece to make PtAnOn+, and it is also thermodynamically favored to then substitute the Pt end with an O atom to make AnO2n+. The calculated +2 charged PtAnO2+ ground states involve higher spin states that were usually formed by unpairing a Pt-An σ (6s-7s) bond and putting the other electron into the 5f shell of the An. A Natural Bond Orbital analysis (NBO) on the PtAnOn+ species suggested a double to quadruple metal-metal bond between the Pt and the An. For the CCI studies, a way of estimating and predicting the dimer stabilities is proposed, the Natural Bond Orbital analysis suggest that rather than the previously accepted Lewis acid-base explanation, CCIs are the direct result of a competition between charge transfer stabilization and Coulombic repulsive destabilization. The predicted thermochemical properties and trends correlate well with experiments in both gas phase and condensed phases

Consistent Improvement on Both Exchange and Correlation within Hybrid Multiconfiguration Pair-density Functional Theory: tB4LYP

The great success of hybrid density functional approximations, e.g.~B3LYP and PBE0, is demonstrated by their substantial improvements over their parent methods, i.e.~the Hartree-Fock approximation and the generalized gradient approximation. They also surpass the second-order M\o{}ller-Plesset perturbation theory (MP2) having a much higher computational cost. Here, we generalize the linear scheme of hybrid multiconfiguration pair-density functional theory (HMC-PDFT) by introducing a cross-entropy approximation to achieve a balanced description of the static and dynamic correlation effects, providing a consistent improvement in describing both exchange and correlation energies. We demonstrated that the B3LYP-like translated on-top functional (tB4LYP) established within the new hybrid scheme is not only more accurate than the parent methods of the complete active space self consistent field (CASSCF) and the pure and hybrid MC-PDFT functional (tBLYP and tB3LYP), but also outdoes the complete active space second-order perturbation theory (CASPT2), which is one of the most popular multi-reference wave-function methods in quantum chemistry. Given that the computational cost of tB4LYP is much cheaper than that of CASPT2, we recommend tB4LYP for the study of complex molecular systems where dynamic and static correlation effects are of comparable importance

Acidity of M(VI)O₂(OH)₂ for M = Group 6, 16, and U as Central Atoms

Gas-phase acidities and aqueous solution p<i>K</i>_a’s are predicted for MO₂(OH)₂, where the center atom M is a main Group 6, 16, and U atom using the Feller–Peterson–Dixon approach based on coupled cluster CCSD­(T) calculations with additional corrections. The gas-phase acidities of the MO₂(OH)₂ compounds are essentially the same for elements (M) of the same group, 304–310 kcal/mol at 298 K. All of the Group 6 compounds are 5–6 kcal/mol less acidic in the gas phase than H₂SO₄. The gas-phase acidity of UO₂(OH)₂ is calculated to be up to 338.0 kcal/mol, ∼10% less acidic in the gas phase than the other MO₂(OH)₂ acids. The most acidic molecule in aqueous solution is predicted to be H₂SO₄. Overall, for the Group 16 compounds, the p<i>K</i>_a’s increase going down the group, with H₂PoO₄ predicted to be slightly more acidic than nitric acid. H₂CrO₄ is the most acidic of the Group 6 transition metal compounds. The aqueous acidities of H₂MoO₄ and H₂WO₄ are comparable and about 3 p<i>K</i>_a units less acidic than H₂CrO₄ and comparable in acidity to HNO₃. H₂UO₄ is not acidic at all in aqueous solution with a p<i>K</i>_a near 20 p<i>K</i>_a units and is also not predicted to readily undergo hydrolysis reactions

Preparation of Ti-46Al-8Nb Alloy Ingots beyond Laboratory Scale Based on BaZrO3 Refractory Crucible

The high Nb-containing TiAl-based alloy ingot beyond laboratory scale with a composition of Ti-46Al-8Nb (at.%) was prepared by a vacuum induction melting process based on a BaZrO3 refractory crucible. A round bar ingot with a diameter of 85 mm and a length of 430 mm was finally obtained, and the chemical composition, solidification pathway, microstructure and tensile properties of the ingot were investigated. The results show that the deviations of Al and Nb content along a 430 mm long central part of the ingot are approximately &plusmn;0.39 at.% and &plusmn;0.14 at.%, and the oxygen content in the ingot can be controlled at around 1000 ppm. The structure of the alloy ingot is a full lamellar structure composed of &gamma; and &alpha;2 phases, and the thickness of the lamellae is approximately 0.53 &mu;m. In case of the &alpha;2 phase, the surface content of the ingot is higher than the middle region and the centrical region; also, it indicated a decreasing trend. During cooling, the alloy solidified from a peritectic reaction (L + &beta;&rarr;&alpha;) rather than the solidified via &beta; phase (&beta;&rarr;&alpha;). In addition to Al segregation and Nb segregation, &beta;-phase particles associated with &gamma; phase at the triple junction of the colonies were observed. Moreover, the tensile properties of the longitudinal-cut sample in the ingot is significantly better than those of the transverse-cut sample, with a tensile strength of up to as high as 700 MPa and a corresponding fracture elongation of 1.1%. However, the tensile strength of the transverse-cut sample is only 375 MPa, and the fracture elongation is 0.52%