The Abundances of Cobalt and Nickel in the Atmosphere of 78 Vir (A2p SrCrEu)

Cobalt and nickel abundances are rarely available for normal and Chemically Peculiar A stars because the strongest transitions of Co ii and Ni ii fall in the mid-UV. The abundances of cobalt and nickel are derived for 78 Vir using a mean mid-ultraviolet spectrum constructed by coadding 10 spectra collected with the Long Wave Prime and Long wavelength Redundant cameras over the 18 yr of the IUE mission. The strong transitions of Co ii at 2286.16 Å, 2307.86 Å, 2324.32 Å and 2580.33 Å and that of Ni ii et 2287.09 Å are present and more or less affected by blends. The least blended, λ 2286.16 Å, yields a mean overabundance of cobalt of 5 times the solar abundance, the Ni ii line at 2287.09 Å yields a 3 times solar overabundance. There is no convincing evidence that these lines varied in the spectra analyzed. The rotational period of 78 Vir estimated from its recent TESS lightcurve is 3.723 ± 0.055 days.

Abundances of Elements Lighter than Scandium in the Atmosphere of the Standard Giant Star α Sex (HD 87887, A0 III)

The abundances of elements lighter than scandium in the atmosphere of the A0 III giant, α Sex, are derived using archival ultraviolet and optical spectra. Most of the strongest lines present in the far-ultraviolet spectrum of α Sex can be attributed to chemical elements lighter than calcium. The synthesis of selected lines in the optical and ultraviolet yields new abundances, in particular for elements which have few lines in the optical range. Helium, oxygen, silicon and sulfur are found to have solar abundances, most other elements are underabundant. Aluminium may be marginally overabundant. The lines of chlorine are probably present in the FUV but they are too blended to derive the abundance of chlorine.

Influence Mechanism of Magnetized Modified Kerosene on Flotation Behavior of Molybdenite

The effects and mechanism of magnetized kerosene on the flotation behaviors of molybdenite were studied by micro-flotation, ultraviolet spectrum, infrared spectrum, surface tension, and liquid viscosity. According to the results of micro-flotation, magnetized kerosene improved the flotation recovery of molybdenite, and the improvements were more obvious with smaller molybdenite particles. Spectral analysis showed that the magnetization did not change the chemical composition of kerosene, but transformed the linear aliphatic hydrocarbons in kerosene into linear isomers and reduced the lengths of the carbon chains. Moreover, the magnetization reduced the viscosity of kerosene and oil/water interfacial tension, and improved the dispersion of kerosene in the pulp. The external magnetic field transformed the disorder of the additional magnetic moment in the kerosene molecules into order, and reduced the compactness of the kerosene molecules. The experimental results provided a theoretical explanation for the role of magnetization in mineral flotation.

Real Structure of Benzene Molecule and the Thickness of Graphene

The problem of benzene molecular structure has not been solved for more than 100 years. This research proposes a new concept of covalent bond based on the existing theory: each electron shared by multiple atom nuclei corresponds to a half-valent bond. The half-valent bond can be formed between the spacer carbon atoms of the benzene ring. In this way, a new theory was established. Quantum mechanical calculations can quantitatively explain experimental results, such as the hydrogenation heat and ultraviolet spectrum of benzene. Using the dotted line to indicate the half-valent bond, benzene molecular structural forms and chemical reaction formulas as will as its dozens of homologues and derivatives are designed easily. The method not only has a wide range of adaptability, but can also record the chemical reaction process. If several stacked benzene rings can form a benzene tube under the guidance of the new theory, calculated thickness of the three-layer benzene tube is very close to the thickness of graphene. Therefore, referring to other characteristics of graphene, it is considered to be more like a three-layer structure.

Highly efficient photoelectric effect in halide perovskites for regenerative electron sources

Electron sources are a critical component in a wide range of applications such as electron-beam accelerator facilities, photomultipliers, and image intensifiers for night vision. We report efficient, regenerative and low-cost electron sources based on solution-processed halide perovskites thin films when they are excited with light with energy equal to or above their bandgap. We measure a quantum efficiency up to 2.2% and a lifetime of more than 25 h. Importantly, even after degradation, the electron emission can be completely regenerated to its maximum efficiency by deposition of a monolayer of Cs. The electron emission from halide perovskites can be tuned over the visible and ultraviolet spectrum, and operates at vacuum levels with pressures at least two-orders higher than in state-of-the-art semiconductor electron sources.