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In this paper, we formed two BC2P/MoS2 van der Waals (vdW) heterostructures, namely BC2P/MoS2-a and -b heterostructures by stacking the MoS2 and BC2P monolayers. First, by analyzing binding energies, flat average differential charge density and elastic constants of two vdW heterostructures, their structures and formation possibility were studied. Two vdW heterostructures are semiconductors with their indirect band gaps as 0.774/1.405 eV and 1.028/1.458 (direct) eV under the GGA-PBE/HSE06 functional, respectively. Moreover, they are two-dimensional materials with close hardness to the graphene. Especially, two vdW heterostructures possess very high absorption coefficients (> 30%) and low reflection coefficients (< 4%) for the visible light, which makes them as novel and potential two-dimensional materials in the application of optoelectronic, electronic and photovoltaics devices. [ABSTRACT FROM AUTHOR]

A macromolecule flocculant polyethyleneimine–sodium xanthogenate, with the capacities of chelation, flocculation and precipitation for Cd(II) ions, was prepared. The effects of some parameters on the removal of Cd(II) by polyethyleneimine–sodium xanthogenate were investigated through flocculation experiments. The results showed that polyethyleneimine–sodium xanthogenate could remove Cd(II) ions effectively, and the removal rate of Cd(II) increased with the increase in pH. The maximum removal rate of Cd(II) increased from 88.5 to 99.7% at pH from 2.0 to 7.5. The presence of inorganic compounds (KCl, NaCl, CaCl2, MgCl2, NaF, NaNO3 and Na2SO4) in the solutions had less impact on the removal of Cd(II), while the existence of organic compounds (EDTA, CA, AA and TSPP) had significant influence on the Cd(II) removal efficiency. Furthermore, the existence of turbidity could improve the Cd(II) removal efficiency, and Cd(II) ions and turbidity in water samples were effectively removed simultaneously. The maximum removal rate of turbidity could reach 99.8%. The results of FTIR spectra and SEM indicated that the chelation between Cd(II) ions and dithiocarboxylic acid groups (–C(=S)–SH) on the molecular chains of polyethyleneimine–sodium xanthogenate was predominant for the removal of Cd(II), and adsorption bridging mechanism among the flocs also played an important role in the flocculation processes. [ABSTRACT FROM AUTHOR]

Quantitative structure-pharmacokinetic/pharmacodynamic (PK/PD) relationship (QSPR) techniques and chemometric methods were employed to classify fluoroquinolones with respect to their activity against Streptococcus pneumoniae. Density functional theory (DFT) was used to calculate a set of molecular descriptors (properties) for 13 synthetic fluoroquinolones. The descriptors were further analyzed using chemometric methods including principal component analysis (PCA), hierarchical cluster analysis (HCA), and stepwise discriminant analysis (SDA). The PCA and SDA methods were employed in order to reduce the dimensionality and select a subset of variables that would be more effective for classifying the fluoroquinolones according to their degree of antipneumococcal activity. The methods of PCA, SDA and HCA were quite efficient to classify 13 compounds in two groups (active and inactive), and the net charge on ring B ( Q B), molecular volume (VOL), and partition coefficient (log P ) were found to be descriptors important for the classification. These methodologies of PCA, SDA and HCA provide a reliable rule for classifying new fluoroquinolones with respect to antipneumococcal activity. The application of the SPP relationship is of considerable value for clinicians, drug developers, and regulators because PK/PD principles form the basis of modern antimicrobial chemotherapy. [ABSTRACT FROM AUTHOR]

Erbium and silicon were dual implanted into thermally grown SiO2 film on Si (110) substrates, followed by thermal treatment at 700-1200 °C for 30 min. The microstructure was studied by transmission electron microscope and x-ray diffraction. When the implanted films were annealed at T > 900 °C, the silicon nanocrystals (nc-Si) enwrapped by amorphous silicon (a-Si) could be observed. The thermal quenching behavior at λ = 1.535 µm and its relation with the annealling temperature were also investigated. With increasing annealing temperature, the portion of a-Si and the thermal quenching both decreased. Efficient luminescence from Er ions and weak intensity thermal quenching were obtained from the sample annealed at 1100 °C. The role of a-Si in non-radiative processes at T > 100 K is discussed. [ABSTRACT FROM AUTHOR]