Conductance oscillation and quantization in monoatomic Al wires

We present first-principles calculations for the transport properties of monoatomic Al wires sandwiched between Al(100) electrodes. The conductance of the monoatomic Al wires oscillates with the number of the constituent atoms as a function of the wire length, either with a period of four-atom for wires with the typical interatomic spacing or a period of six-atom with the interatomic spacing of the bulk fcc aluminum, indicating a dependence of the period of conductance oscillation on the interatomic distance of the monoatomic Al wires

Near-Infrared (NIR) Luminescent Homoleptic Lanthanide Salen Complexes Ln(4)(Salen)(4) (Ln = Nd, Yb Or Er)

The series of homoleptic tetranuclear [Ln(4)(L)(2)(HL)(2)(NO3)(2)(OH)(2)]center dot 2(NO3) (Ln = Nd, 1; Ln = Yb, 2; Ln = Er, 3; Ln = Gd, 4) have been self-assembled from the reaction of the Salen-type Schiff-base ligand H2L with Ln(NO3)(3)center dot 6H(2)O (Ln = Nd, Yb, Er or Gd), respectively (H2L: N, N'-bis(salicylidene) cyclohexane-1,2-diamine). The result of their photophysical properties shows that the strong and characteristic NIR luminescence for complexes 1 and 2 with emissive lifetimes in microsecond ranges are observed and the sensitization arises from the excited state (both (LC)-L-1 and (LC)-L-3) of the Salen-type Schiff-base ligand with the flexible linker.National Natural Science Foundation 21173165, 20871098Ministry of Education of China NCET-10-0936Higher Education of China 20116101110003State Key Laboratory of Structure Chemistry 20100014Education Committee Foundation of Shaanxi Province 11JK0588Hong Kong Research Grants Council, P. R. of China HKBU 202407, FRG/06-07/II-16)Hong Kong Research Grants Council, Robert A. Welch Foundation F-816Texas Higher Education Coordinating Board ARP 003658-0010-2006Petroleum Research Fund 47014-AC5Chemistr

Time Series Feature Selection Method Based on Mutual Information

Time series data have characteristics such as high dimensionality, excessive noise, data imbalance, etc. In the data preprocessing process, feature selection plays an important role in the quantitative analysis of multidimensional time series data. Aiming at the problem of feature selection of multidimensional time series data, a feature selection method for time series based on mutual information (MI) is proposed. One of the difficulties of traditional MI methods is in searching for a suitable target variable. To address this issue, the main innovation of this paper is the hybridization of principal component analysis (PCA) and kernel regression (KR) methods based on MI. Firstly, based on historical operational data, quantifiable system operability is constructed using PCA and KR. The next step is to use the constructed system operability as the target variable for MI analysis to extract the most useful features for the system data analysis. In order to verify the effectiveness of the method, an experiment is conducted on the CMAPSS engine dataset, and the effectiveness of condition recognition is tested based on the extracted features. The results indicate that the proposed method can effectively achieve feature extraction of high-dimensional monitoring data

Electronic, Magnetic, and Catalytic Properties of Thermodynamically Stable Two-Dimensional Transition-Metal Phosphides

Two-dimensional (2D) nanomaterials have attracted extensive interest due to their unique properties and versatile applications. In the current work, a new family of 2D nanostructures, 2D transition-metal phosphide monolayer (M₂P), is designed to find its multifunctional applications on the basis of density functional theory (DFT) calculations. We show that the 2D M₂P monolayers are thermodynamically stable by carrying out molecular dynamic simulations, analyzing their phonon dispersions, and calculating their mechanical properties. We find that all of the stable 2D M₂P monolayers are metallic, and their magnetic states strongly depend on the transition metals and geometric phases. We further demonstrate that 2D W₂P and Fe₂P monolayers in the 2H phase show the best catalytic performance in hydrogen evolution reaction (HER) due to the relatively low overpotentials at high hydrogen coverage. Importantly, oxygen functionalization can efficiently improve the HER activities of the 2D M₂P monolayers at low hydrogen coverage. Our systematic study predicts that these new thermodynamically stable 2D transition-metal phosphides could be applicable in nanodevices, spintronics, and electrocatalysis