Propagation of Electromagnetic Waves in Cholesteric Liquid Crystals

2021 ◽  
Author(s):  
K. R. Dossumbekov ◽  
N. A. Ispulov ◽  
A. A. Kurmanov ◽  
A. Zh. Zhumabekov
Keyword(s):  
Liquid Crystals ◽  
Electromagnetic Waves ◽  
Cholesteric Liquid Crystals

Propagation of electromagnetic waves in a cholesteric liquid crystals

2021 ◽  
pp. 9-15
Author(s):  
K.R. Dossumbekov ◽  
◽  
N.A. Ispulov ◽  
A.A. Kurmanov ◽  
A.Zh. Zhumabekov
Keyword(s):  
Liquid Crystals ◽  
Electromagnetic Waves ◽  
Cholesteric Liquid Crystals

scholarly journals Features of dielectric properties of medical thermal indicators based on dispersions of cholesteric liquid crystals in the polymer matrix

2020 ◽  
Vol 23 (04) ◽  
pp. 372-378
Author(s):  
O.V. Kovalchuk ◽  
◽  
V.Yo. Kotovskyi ◽  
V.E. Ovcharek ◽  
I.V. Oleinikova ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Dielectric Properties ◽  
Human Body ◽  
Electromagnetic Waves ◽  
Polyvinyl Acetate ◽  
Cholesteric Liquid Crystals ◽  
Selective Reflection ◽  
The Difference ◽  
Thermal Indicators ◽  
Frequency Dependences

Within the frequency range 10…106 Hz, the frequency dependences of the real (ε') and imaginary (ε") components of the complex dielectric permittivity of medical thermal indicators based on polyvinyl acetate and mixtures of cholesteric liquid crystals have been studied. In them, the selective reflection of electromagnetic waves visible to the human eye occurs at normal (36.6 °C) and elevated (38.2 °C) human body temperatures. Being based on the comparison of the ε' frequency dependences for the studied in this work dispersions of nematic liquid crystals prepared using the same technology and with the same polymer, it has been shown that, already on the basis of analysis of frequency dependences for ε', it is possible to ascertain the difference in characteristics for two types of thermal indicators. From the comparison of frequency dependences for ε", the main reasons of a difference between dielectric properties of the investigated medical thermal indicators for various temperatures of a human body have been ascertained.

scholarly journals Synthesis and Characterization of Novel Bio-Chiral Dopants Obtained from Bio-Betulin Produced by a Fermentation Process

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 785
Author(s):  
Veridiana G. Guimarães ◽  
Anastasiia Svanidze ◽  
Tianyi Guo ◽  
Pawan Nepal ◽  
Robert J. Twieg ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Natural Product ◽  
Fermentation Process ◽  
Synthesis And Characterization ◽  
Cholesteric Liquid Crystals ◽  
And Performance ◽  
Chiral Dopants

Cholesteric liquid crystals are frequently produced by the addition of chiral dopants to achiral nematic hosts. We report here the synthesis and performance of chiral dopants obtained from bio-betulin produced by a fermentation process. An important aspect of this work is to point out that the fermentation process used to obtain the starting materials is much easier and cheaper when carried out in large volumes than isolating it from the natural product. The performance of the dopants obtained from bio-betulin is indistinguishable from those obtained from commercially available synthetic betulin.

scholarly journals Augmented Lagrangian preconditioners for the Oseen–Frank model of nematic and cholesteric liquid crystals

2021 ◽  
Author(s):  
Jingmin Xia ◽  
Patrick E. Farrell ◽  
Florian Wechsung
Keyword(s):  
Liquid Crystals ◽  
Augmented Lagrangian ◽  
Augmented Lagrangian Method ◽  
Mass Matrix ◽  
Unit Length ◽  
Mesh Size ◽  
Schur Complement ◽  
Cholesteric Liquid Crystals ◽  
Multigrid Algorithm ◽  
The Cost

AbstractWe propose a robust and efficient augmented Lagrangian-type preconditioner for solving linearizations of the Oseen–Frank model arising in nematic and cholesteric liquid crystals. By applying the augmented Lagrangian method, the Schur complement of the director block can be better approximated by the weighted mass matrix of the Lagrange multiplier, at the cost of making the augmented director block harder to solve. In order to solve the augmented director block, we develop a robust multigrid algorithm which includes an additive Schwarz relaxation that captures a pointwise version of the kernel of the semi-definite term. Furthermore, we prove that the augmented Lagrangian term improves the discrete enforcement of the unit-length constraint. Numerical experiments verify the efficiency of the algorithm and its robustness with respect to problem-related parameters (Frank constants and cholesteric pitch) and the mesh size.

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