Monitoring the emergence of antibiotic resistance using the technology ot the DebugIT platform in the HEGP context

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Non linear dielectric spectroscopy: a method to determine physical parameters of ferroelectric liquid crystals

This paper concerns non linear dielectric spectroscopy in the SmC* phase of a ferroelectric liquid crystal. The experimental set-up and the procedure used to determine non linear permittivities are described. The results are discussed on the basis of the model proposed by Kimura et al. [Y. Kimura, S. Hara, R. Hayakawa, Phys. Rev. E 62, R5907 (2000); Y. Kimura, S. Hara, R. Hayakawa, Ferroelectrics 245, 61 (2000)]. A good agreement is obtained between the measurements and the theoretical predictions for $\epsilon^{*}_{3,3}$ and $\epsilon^{*}_{5,5}$ non linear permittivities. Some physical parameters of the material like the polarization, the rotational viscosity and the elastic term are determined. The polarization is found similar to this obtained with classical triangular wave method

Dynamics of Nematogenic Molecules with Transverse Component of Dipole Moment

The paper presents the results of studies of the dielectric relaxation of nematic 4'-butyloxy-3-fluoro- 4-isothiocyanatotolane, performed for different values of the angle between the probing electric field E and the macroscopic orientation of the sample (the director n) forced by the magnetic field B. Due to a relatively large transverse component of the dipole moment of 4'-butyloxy- 3-fluoro-4-isothiocyanatotolane, the studies allowed one to interpret consistently the dielectric relaxation spectra connected with the molecular rotation around the long axis

Analog set-up for non linear dielectric measurements up to 100 kHz

In this paper, we present a new analog set-up for non linear dielectric measurements. The device is based on the auto-balanced bridge principle used in impedance analyzers. Its main advantage is to operate at high frequencies in comparison with a classical current amplifier. This extension consists in extracting the harmonics of a non sinusoidal current crossing the material. The set-up is used to perform non linear dielectric measurements on a ferroelectric liquid crystal and shows better performances than a previously published digital set-up

Molecular Dynamics of 4-(trans-4'-n-Heptylcyclohexyl)- Isothiocyanatobenzene Studied with Dielectric Relaxation Spectroscopy

Dielectric relaxation study was carried out for the nematic and isotropic phases of 4-(trans-4'-n- heptylcyclohexyl)isothiocyanatobenzene in the frequency range from 100 kHz to 1 GHz. In the nematic phase two relaxation processes were recorded for the electric permittivity component measured parallel to the molecular orientation (director n) and three relaxation processes - for the perpendicular permittivity component. The strength of the nematic potential and the nematic order parameter were estimated

On the phase transitions of 8CB/Sn

Using differential scanning calorimetry measurements, the influence of Sn2P2S6 ferroelectric nanoparticles on the phase transition temperatures of the 8CB liquid crystal is studied. The spontaneous polarization, ionic and anchoring effects are discussed. For low concentration of dopant, the global effect leads to a decrease and an increase of the nematic-isotropic and the smectic A-nematic phase transition temperatures, respectively. For high concentrations, due to aggregates formation, the predominant anchoring effect induces a decrease of the both phase transition temperatures

Propriétés électro-optiques et électriques de suspensions de nanoparticules ferroélectriques dans une matrice cristal liquide

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