Etude structurale et vibrationnelle d'un nouveau composé complexe de cobalt: [Co(imidazole)4Cl]Cl.

In the title complex, chlorido-tetra-kis-(1H-imidazole-κN (3))cobalt(II) chloride, [CoCl(C3H4N2)4]Cl, the Co(II) cation has a distorted square-pyramidal coordination environment. It is coordinated by four N atoms of four imidazole (Im) groups in the basal plane, and by a Cl atom in the apical position. It is isostructural with [Cu(Im)4Cl]Cl [Morzyk-Ociepa et al. (2012 ▸). J. Mol. Struct. 1028, 49-56] and [Cu(Im)4Br]Br [Hossaini Sadr et al. (2004 ▸). Acta Cryst. E60, m1324-m1326]. In the crystal, the [CoCl(C3H4N2)4](+) cations and Cl(-) anions are linked via N-H⋯Cl hydrogen bonds, forming layers parallel to (010). These layers are linked via C-H⋯Cl hydrogen bonds and C-H⋯π and π-π [inter-centroid distance = 3.794 (2) Å] inter-actions, forming a three-dimensional framework. The IR spectrum shows vibrational bands typical for imidazol groups. The monoclinic unit cell of the title compound emulates an ortho-rhom-bic cell as its ß angle is close to 90°. The crystal is twinned, with the refined ratio of twin components being 0.569 (1):0.431 (1).

Wavelet filtering based on Mellin transform dedicated to cochlear prostheses.

Current speech processing strategies for cochlear prosthesis system use filter bank structure in order to extract speech signal's energies relatively to the multiple frequency bands which are associated to the dedicated stimulation electrodes. This research concerned wavelet filtering module based on Mellin transform and dedicated to one cochlear speech processing strategy. Our bank filtering module was composed of twenty one filters designed according to Morlet mother wavelet and distributed along the Munich critical bands. Hence, our considered auditory spectrum would be divided into twenty one critical frequency bands according to ERB model (Equivalent Rectangular Bandwidth) which would be similar to auditory model. Continuous wavelet transform based Filters' outputs would processed in order to provide the relatively energy levels which would be considered as the targeted stimulation levels. Mellin transform used in this processing permitted a fast algorithm execution compared to one standard CWT based filtering module. Algorithm validation was approved using different input signals as pure harmonics first and then real speech signals extracted from TIMIT database. Our proposed strategy ensures not only execution rapidity but also flexibility in programming, easiness in use as well as different safety features that could help reaching each individual's needs.