Theoretical and experimental study of the orientational ordering in the field-induced intermediaite phase from the SmC*FI2 phase in chiral smectic liquid crystals

Under an electric field, chiral smectic liquid crystals transit usually to the unwound SmC* phase where the helical structure is completely unrolled. Sometimes the sample transits initially towards an intermediate polar state before the total destruction of the helix. Based on the extension of the H-T model, a theoretical study of these field-induced phase transitions was carried out. Two hypotheses of the dynamics that give rise to the appearance of the intermediate phase have been discussed. The results of a numerical analysis confirm the known experimental results; the intermediate phase has a three-layer periodicity structure

Comparative Study of Human and Automated Screening for Antinuclear Antibodies by Immunofluorescence on HEp-2 Cells

Background: Several automated systems had been developed in order to reduce inter-observer variability in indirect immunofluorescence (IIF) interpretation. We aimed to evaluate the performance of a processing system in antinuclear antibodies (ANA) screening on HEp-2 cells. Patients and Methods: This study included 64 ANA-positive sera and 107 ANA-negative sera that underwent IIF on two commercial kits of HEp-2 cells (BioSystems® and Euroimmun®). IIF results were compared with a novel automated interpretation system, the “CyclopusCADImmuno®” (CAD). Results: All ANA-positive sera images were recognized as positive by CAD (sensitivity = 100%), while 17 (15.9%) of the ANA-negative sera images were interpreted as positive (specificity = 84.1%), =0.799 (SD=0.045). Comparison of IIF pattern determination between human and CAD system revealed on HEp-2 (BioSystems®), a complete concordance in 6 (9.37%) sera, a partial concordance (sharing of at least 1 pattern) in 42 (65.6%) cases and in 16 (25%) sera the pattern interpretation was discordant. Similarly, on HEp-2 (Euroimmun®) the concordance in pattern interpretation was total in 5 (7.8%) sera, partial in 39 (60.9%) and absent in 20 (31.25%). For both tested HEp-2 cells kits agreement was enhanced for the most common patterns, homogenous, fine speckled and coarse speckled. While there was an issue in identification of nucleolar, dots and nuclear membranous patterns by CAD. Conclusion: Assessment of ANA by IIF on HEp-2 cells using the automated interpretation system, the “CyclopusCADImmuno®” is a reliable method for positive/negative differentiation. Continuous integration of IIF images would improve the pattern identification by the CAD

Synthesis, characterisation and behaviour under a field of a chiral smectic liquid crystal

The C12HH compound has been synthesised and the phase transition temperatures were obtained by combining several experimental techniques. This compound exhibits in volume all of the tilted smectic phases except the SmC* phase and presents a large SmC* range. The experimental results show unexpected behaviour in planar cell capacitors: (i) compared with the bulk, the SmC* range extends to lower temperature where it coexists with another phase; this demixing phenomenon is not due to a thickness effect but probably induced by a polarisation effect; (ii) the unwinding process of the ferroelectric SmC* phase occurs via two steps with an intermediate state (or phase). The E – T diagram of C12HH has been established except in the region where the coexistence occurs

Speed and current control of permanent magnet synchronous motor drive using IMC controllers

The paper describes a current and speed control of the permanent magnet synchronous motor with vector control. For a current and speed controller, the Internal Model Control (IMC) method was chosen for its good tracking capability and demands on the controllers. A short analysis of the IMC method for design of the current and speed controller has been made. The paper contains mathematical description of the IMC controller design. Simulation and experimental results of the vector controlled AC drive with interior permanent magnet synchronous motor are shown to present features of the current and speed controller.Web of Science12410