Accurate Force Field for Molybdenum by Machine Learning Large Materials Data

In this work, we present a highly accurate spectral neighbor analysis potential (SNAP) model for molybdenum (Mo) developed through the rigorous application of machine learning techniques on large materials data sets. Despite Mo's importance as a structural metal, existing force fields for Mo based on the embedded atom and modified embedded atom methods still do not provide satisfactory accuracy on many properties. We will show that by fitting to the energies, forces and stress tensors of a large density functional theory (DFT)-computed dataset on a diverse set of Mo structures, a Mo SNAP model can be developed that achieves close to DFT accuracy in the prediction of a broad range of properties, including energies, forces, stresses, elastic constants, melting point, phonon spectra, surface energies, grain boundary energies, etc. We will outline a systematic model development process, which includes a rigorous approach to structural selection based on principal component analysis, as well as a differential evolution algorithm for optimizing the hyperparameters in the model fitting so that both the model error and the property prediction error can be simultaneously lowered. We expect that this newly developed Mo SNAP model will find broad applications in large-scale, long-time scale simulations.Comment: 25 pages, 9 figure

Systematical research on the aerodynamic noise of the high-lift airfoil based on FW-H method

In numerical computation of aerodynamic noises, the solution accuracy of flow fields has an obvious impact on detailed computation of eddy turbulence and acoustic results. In this paper, LES (Large Eddy Simulation) was used to conduct numerical simulation of flow fields of three-dimensional high-lift L1T2 airfoil. Unsteady flow field data on the solid wall face was extracted as the noise source. The integration method FW-H (Ffowcs Williams-Hawkings) was used to compute far-field noises. The numerical computation method was verified by experiments. Results show that: the numerical computation method used in this paper can provide an accurate solution for computing far-field aerodynamic noises. Finally, based on the verified numerical model, contribution amounts made by each high-lift airfoil component to noises as well as major factors affecting aerodynamic noises were analyzed. Computational results show that: the leading edge slats generated aerodynamic noises mainly because of the unsteady waves which were caused by the grooves between the slat and main wing, as well as small wake eddies generated on the trailing edge of slats; flaps generated aerodynamic noises mainly because of mixing between high-frequency small-scale eddies and low-frequency large-scale eddies caused by flow separation around the wing flaps. Acoustic directivity of leading edge slats and trailing edge flaps showed an obvious dipole characteristic. For both of them, the sound pressure levels reached the maximum value in the direction perpendicular to the chord line

Dichlorido(4′-ferrocenyl-2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)zinc acetonitrile monosolvate

The title complex, [FeZn(C5H5)Cl2(C20H14N3)]·CH3CN, is composed of one ZnII atom, one 4′-ferrocenyl-2,2′:6′,2′′-terpyridine (fctpy) ligand, two Cl atoms and one acetonitrile solvent mol­ecule. The ZnII atom is five-coordinated in a trigonal–bipyramidal geometry by the tridentate chelating fctpy ligand and two Cl atoms

Optimized Design on the Width and Spacing of the Cross Passageway in Tunnels

AbstractCross passageways have been commonly applied in the evacuation system of tunnels, and the width and spacing of the cross passageways decide the evacuation capacity of the tunnel. In design, increasing the width of the cross passageways and reducing their spacing can improve the evacuation ability of tunnels. However, it will certainly increase the cost of the project. Under the precondition of meeting evacuation requirements, an optimization model was established in this article, which aimed at reducing the cost of the project. Finally, discussions on the application of this optimization model were carried on, and this method may provide reference for designing cross passageways

(4′-Ferrocenyl-2,2′:6′,2′′-terpyridine-κ3 N 1,N 1′,N 1′′)(1,10-phenanthroline-κ2 N,N′)zinc(II) bis­(perchlorate) acetonitrile monosolvate

In the title complex, [FeZn(C5H5)(C20H14N3)(C12H8N2)](ClO4)2·CH3CN, the ZnII atom is five-coordinated by a tridentate chelating 4′-ferrocenyl-2,2′:6′,2′′-terpyridine (fctpy) ligand and a bidentate chelating 1,10-phenanthroline (phen) ligand in a distorted square-pyramidal environment with a phen N atom located at the apical position [Zn—N = 2.259 (4) Å]. The terpyridyl motif in each fctpy ligand is coplanar, but the cyclo­penta­dienyl ring is twisted by 9.5 (2)° out of coplanarity with each central pyridine. The two cyclo­penta­dienyl rings of the ferrocenyl group are almost eclipsed with a deviation of 4.5 (1)°. In addition, inter­molecular π–π inter­actions [centroid–centroid distance 3.753 (2) Å] are present between the cyclo­penta­dienyl and outer pyridyl rings of the fctpy ligands. One of the perchlorate anions is equally disordered over two positions

5,7-Dihydr­oxy-3,6,8-trimethoxy­flavone

The title compound (systematic name: 5,7-dihydr­oxy-3,6,8-trimeth­oxy-4H-chromen-4-one), C18H16O7, is a flavone that was isolated from Ainsliaea henryi. There are two mol­ecules in the asymmetric unit, one of which has a disordered meth­oxy group [occupancy ratio 0.681 (9):0.319 (9)]. Both mol­ecules have an intra­molecular O—H⋯O hydrogen bond. In the crystal, mol­ecules are linked into O—H⋯O hydrogen-bonded chains parallel to [110]

(4′-Ferrocenyl-2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)(1,10-phenanthroline-κ2 N,N′)copper(II) bis(perchlorate) acetonitrile solvate

The title complex, [CuFe(C5H5)(C20H14N3)(C12H8N2)](ClO4)2·C2H3N, consists of a mononuclear [Cu(C12H8N2)(C25H19FeN3)]2+ cation, two ClO4 − anions (one of which is disordered over two positions with equal occupancy) and one CH3CN solvent mol­ecule. The CuII center has a distorted square-pyramidal coordination with three N atoms of the 4′-ferrocenyl-2,2′:6′,2′′- terpyridine (fctpy) ligand and one 1,10-phenanthroline (phen) N atom in the basal plane and a second phen N atom in the apical position with an axial distance of 2.254 (4) Å. The disordered ClO4 − anion is weakly coordin­ated to the CuII ion with a Cu—O distance of 2.766 (11) Å. The two cyclo­penta­dienyl rings of the ferrocenyl group are almost eclipsed with a deviation of 4.7 (1) °, and are involved in inter­molecular π–π inter­actions with the outer pyridyl rings of the fctpy ligands [centroid–centroid distance = 3.759 (2) Å.]

Preparation of total triterpenoids from Antrodia cinnamomea fermentation mycelium and their in vitro inhibitory effects on hepatocellular carcinoma

Abstract Total triterpenoids from Antrodia cinnamomea fermentation mycelium (TT-ACFM) were prepared, and their in vitro inhibitory effects on hepatocellular carcinoma were investigated. Human hepatocellular carcinoma HepG2 cells were incubated with TT-ACFM with concentration of 0 (control), 12.5, 25, 50, 100 and 200 μg/mL, respectively. The proliferation of cell was detected using CCK-8 method. The apoptosis of cells was detected by flow cytometry. The migration and invasion of cells was determined using Transwell chamber. The level of reactive oxygen species (ROS) in cells was determined using DCFH-DA method. The expressions of matrix metalloproteinse-2 (MMP-2), matrix metalloproteinse-9 (MMP-9) and vascular endothelial growth factor (VEGF) protein in cells were detected by western blot assays. Results indicate that, TT-ACFM can not only inhibit the proliferation of HepG2 cells and promote their apoptosis, but also inhibit their invasion and invasion. The mechanism may be related to its increase of ROS and down-regulation of MMP-2, MMP-9 and VEGF expression in cells