4,4′-Bipyridine–2-meth­oxy­benzoic acid (1/2)

The asymmetric unit of the title compound, C10H8N2·2C8H8O3, contains two 2-meth­oxy­benzoic acid mol­ecules and one 4,4′-bipyridine mol­ecule. The 4,4′-bipyridine mol­ecule is disordered over two positions in a 1:1 ratio. In the crystal, the 2-meth­oxy­benzoic acid and 4,4′-bipyridine mol­ecules are connected by inter­molecular O—H⋯N hydrogen bonds. The dihedral angle between the carboxy group and its attached ring is 26.823 (2)°

Robust Sound Event Classification using Deep Neural Networks

The automatic recognition of sound events by computers is an important aspect of emerging applications such as automated surveillance, machine hearing and auditory scene understanding. Recent advances in machine learning, as well as in computational models of the human auditory system, have contributed to advances in this increasingly popular research field. Robust sound event classification, the ability to recognise sounds under real-world noisy conditions, is an especially challenging task. Classification methods translated from the speech recognition domain, using features such as mel-frequency cepstral coefficients, have been shown to perform reasonably well for the sound event classification task, although spectrogram-based or auditory image analysis techniques reportedly achieve superior performance in noise. This paper outlines a sound event classification framework that compares auditory image front end features with spectrogram image-based front end features, using support vector machine and deep neural network classifiers. Performance is evaluated on a standard robust classification task in different levels of corrupting noise, and with several system enhancements, and shown to compare very well with current state-of-the-art classification techniques

Formation of Nanofoam carbon and re-emergence of Superconductivity in compressed CaC6

Pressure can tune material's electronic properties and control its quantum state, making some systems present disconnected superconducting region as observed in iron chalcogenides and heavy fermion CeCu2Si2. For CaC6 superconductor (Tc of 11.5 K), applying pressure first Tc increases and then suppresses and the superconductivity of this compound is eventually disappeared at about 18 GPa. Here, we report a theoretical finding of the re-emergence of superconductivity in heavily compressed CaC6. The predicted phase III (space group Pmmn) with formation of carbon nanofoam is found to be stable at wide pressure range with a Tc up to 14.7 K at 78 GPa. Diamond-like carbon structure is adhered to the phase IV (Cmcm) for compressed CaC6 after 126 GPa, which has bad metallic behavior, indicating again departure from superconductivity. Re-emerged superconductivity in compressed CaC6 paves a new way to design new-type superconductor by inserting metal into nanoporous host lattice.Comment: 31 pages, 12 figures, and 4 table

A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz

A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz is carried out using the Shanghai Tian Ma 65 m Radio Telescope (TMRT-65m) with a sensitivity of < 7 mK. Thirty-five spectral lines of 12 different molecules and radicals are detected in total. Except for SiS, the detected molecules are all carbon-chain molecules, including HC3N, HC5N, HC7N, HC9N, C6H, C6H-, C8H, SiC2, SiC4, c-C3H2 and l-C5H. The presence of rich carbon-bearing molecules is consistent with the identity of IRC +10216 as a carbon-rich AGB star. The excitation temperatures and column densities of the observed species are derived by assuming a local thermodynamic equilibrium and homogeneous conditions.Comment: This is the authors' version of the manuscript; 16 pages, 5 figures, 6 tables; Accepted for publication in A&A 8/17/201

1-(2-Chloro­benzyl­idene)-2-(2,4-dinitro­phen­yl)hydrazine

In the title compound, C13H9ClN4O4, there are two crystallographically independent mol­ecules in the asymmetric unit, which have very similar conformations. The C=N—N angles in each independent mol­ecule are 115.0 (2) and 116.6 (2)°, which are significantly smaller than the ideal value of 120° expected for sp 2-hybridized N atoms. This is probably a consequence of repulsion between the nitro­gen lone pairs and the adjacent N—N bonds. Two bifurcated intra­molecular N—H⋯O hydrogen bonds help to establish the mol­ecular conformation and consolidate the crystal packing