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The numerical ill‐conditioning associated with approximating an electron density with a convex sum of Gaussian or Slater‐type functions is overcome by using the (extended) Kullback–Leibler divergence to measure the deviation between the target and approximate density. The optimized densities are non‐negative and normalized, and they are accurate enough to be used in applications related to molecular similarity, the topology of the electron density, and numerical molecular integration. This robust, efficient, and general approach can be used to fit any non‐negative normalized functions (e.g., the kinetic energy density and molecular electron density) to a convex sum of non‐negative basis functions. We present a fixed‐point iteration method for optimizing the Kullback–Leibler divergence and compare it to conventional gradient‐based optimization methods. These algorithms are released through the free and open‐source BFit package, which also includes a L2‐norm squared optimization routine applicable to any square‐integrable scalar function. [ABSTRACT FROM AUTHOR]

Power supply system plays an important role in the operation of urban rail systems. It has to provide high‐quality energy for trains continuously. Train's energy consumption is varied directly with operation conditions such as train's headway, train configuration, line characteristic and many other factors. Therefore, using a powerful simulation tool for estimating energy consumption considering these factors seems inevitable. This paper tries to develop a hybrid model in which the train model is based on acquired data from real measurement and an adapted network electrical model. Train empirical model is based on neural network on the basis of online data measured in line one of Shiraz metro and used for training of model. Then benefiting from optimization algorithms, a novel model of energy supply system of trains, including Traction Substations (TSS) and Overhead Catenary System (OCS), is proposed. Finally, the behaviour of trains during operation in 15‐min headway was simulated and the results under same conditions were compared with practical measurements. Currently, this model helps to determine power system behaviour during different operation conditions, predicting energy consumption for different headways, Train's driver behaviour during acceleration, deceleration and braking and also operation risk analysis during traction substations outages. [ABSTRACT FROM AUTHOR]

A relatively simple experimental procedure is proposed for the simultaneous detection and quantitative assessment of moxifloxacin (Moxi) as an example for an antibiotic using surface‐enhanced Raman spectroscopy (SERS) performed in a Kretschmann configuration (KC). The example of Moxi shows the advantage of this approach, such as high sensitivity and relatively simple experimental procedure. The Moxi was reliably detected at levels of 100 nM using excitation laser powers as low as a few milliwatts. We also demonstrate that in the KC, the direct coupling between the electronic systems of analyte molecules and metal substrate contributing to the chemical enhancement mechanism in SERS plays a major role. For this, we have performed simulations based on density functional theory (DFT). The line profile of the SERS spectra can be explained by the direct coupling of molecular sites to the metal. This adds to the molecular specificity of SERS when using the KC. [ABSTRACT FROM AUTHOR]

IOData is a free and open‐source Python library for parsing, storing, and converting various file formats commonly used by quantum chemistry, molecular dynamics, and plane‐wave density‐functional‐theory software programs. In addition, IOData supports a flexible framework for generating input files for various software packages. While designed and released for stand‐alone use, its original purpose was to facilitate the interoperability of various modules in the HORTON and ChemTools software packages with external (third‐party) molecular quantum chemistry and solid‐state density‐functional‐theory packages. IOData is designed to be easy to use, maintain, and extend; this is why we wrote IOData in Python and adopted many principles of modern software development, including comprehensive documentation, extensive testing, continuous integration/delivery protocols, and package management. This article is the official release note of the IOData library. [ABSTRACT FROM AUTHOR]

A terbium–organic framework (Tb‐MOF) was prepared using a previously reported procedure. Tb‐MOF was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, powder X‐ray diffraction and surface area analysis. Tb‐MOF was employed as a heterogeneous Lewis acid catalyst for the synthesis of β‐aminoalcohols. Also, the effect of ultrasonic irradiation was examined in the catalytic aminolysis of styrene oxide. The reaction conditions were optimized by variation of reaction time, catalyst concentration and solvent. Avariety of β‐aminoalcohols were synthesized and characterized. The Tb‐MOF catalyst showed excellent selectivity and high yield for these transformations. [ABSTRACT FROM AUTHOR]

Using a Kretschmann configuration-based setup, surface-enhanced Raman scattering (SERS) experiments have been performed on a monolayer of Nile blue. The experiment has been optimized to achieve reproducible conditions. Laser excitation resulted in a fast decay of the Raman line intensities ending at a stable signal level. We have analyzed this intensity variation mode specifically. The Raman deactivation rate was found to be different for different vibrational modes where high-wavenumber vibrations showed slower decay than the group of low-wavenumber modes. SERS spectra were obtained excluding the contribution of this deactivation process for different angles of incidence of the exciting laser beam. The variation of the surface plasmon excitation in the thin silver film coated onto the prism surface of the Kretschmann configuration resulted in drastically different relative enhancements of the different Raman modes pointing to a major contribution of the chemical enhancement mechanism in the single-layer SERS experiment. The enhancement was found to be mode-specific. High-wavenumber modes showed a stronger enhancement than the low-wavenumber group. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the title compound, C(9)H(8)N(2), a mirror plane lies perpendicular to the phenyl and imidazole rings and passes through the bridging C-C bond, so that the imidazole ring is disordered over two sites about the mirror plane with the equal site occupancy; the asymmetric unit contains one half-mol-ecule. In the crystal, adjacent mol-ecules are linked via N-H⋯N hydrogen bonds.

In the polymeric title compound, [HgCl(2)(C(5)H(5)N(3)O)(2)](n), the Hg(II) atom (site symmetry ) adopts a distorted trans-HgN(2)Cl(4) octa-hedral coordination geometry. In the crystal, adjacent mercury ions are bridged by pairs of chloride ions, generating infinite [100] chains, and N-H⋯O and N-H⋯(N,N) hydrogen bonds help to consolidate the packing.

In the crystal structure of the title compound, [HgBr(2)(C(5)H(5)N(3)O)(2)](n), the Hg(II) cation is located on an inversion center and is coordinated by two N atoms from the pyrazine rings and four bridging Br(-) anions in a distorted octa-hedral geometry. The Br(-) anions bridge the Hg(II) cations with significantly different Hg-Br bond distances of 2.4775 (8) and 3.1122 (8) Å, forming polymeric chains running along the a axis. Inter-molecular N-H⋯O and N-H⋯N hydrogen bonds are effective in the stabilization of the crystal structure.