35 research outputs found
Novel fluorescent liquid crystal containing azobenzene and stilbene moieties-synthesis, mesogenic and spectroscopic studies
Mesogenic properties and studies of the photoisomerization process in solutions of branched azobenzene derivatives with ester group
Monotropic or enantiotropic mesophases? Liquid-crystalline and solid state polymorphism 4-Chloro-1,3-phenylene bis-[4-(4-alkyloxyphenylazo)benzoates
Liquid-crystalline polymorphism of 4-heptyloxybenzylidene-4′-alkyloxyanilines and their phase equilibrium with 4-octyloxyphenyl 4-nitrobenzoate
Liquid-crystalline polymorphism of 4-alkyloxybenzylidene-4′-alkyloxyanilines and nonlinearity of their phase diagrams with different standards
Thermo-optical analysis (TOA) as a tool of melting phenomena investigations
In the work, after preliminary discussion of the complexity of the phenomenon
of melting chemical compounds, two basic research methods are presented: calorimetric
methods and thermooptical method. The physical basis of the five main calorimetry techniques is now detailed (adiabatic calorimetry, differential
thermal
analysis – DTA, differential scanning calorimetry with heat compensation – DSC
heat compensated, differential scanning calorimetry with heat flow – DSC heat flux
and differential scanning calorimetry with temperature modulation – MDSC) and
thermo-optical techniques used in phase transitions investigations. The advantages
and disadvantages of these methods are shown in numerous examples and the accuracy
attainable by the individual measuring techniques is compared
Distinguishing the Focal-Conic Fan Texture of Smectic A from the Focal-Conic Fan Texture of Smectic B
This publication presents methods of distinguishing the focal texture of the conical smectic phase A (SmA) and the crystalline smectic B phase (CrB). Most often, characteristic transition bars are observed in polarized light at the temperature point of the SmA–CrB phase transition. TOApy software transforms each image from a series of images recorded during POM observation to a function of light intensity versus temperature. Thermo-optical analysis is a powerful quantitative tool to notice this phase transition, but it has some limitations. The other applied method, the local binary pattern (LBP) algorithm, with high probability, detects differences between the textures of the conical focal fan of the SmA and CrB phases. The LBP algorithm is an efficient tool for texture classification
