Dielectric Torque and Orientation Dynamics of Liquid Crystals with Dielectric Dispersion

Yin, Ye; Shiyanovskii, Sergij V.; Golovin, Andrii B.; Lavrentovich, Oleg D.

doi:10.1103/physrevlett.95.087801

Cited by 30 publications

(59 citation statements)

References 11 publications

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“…The extracted proteins were digested in a trypsin solution at 37°C for 16 h. Afterwards, the peptides extraction was done with a solution of 50% acetonitrile and 5% formic acid (Yin et al 2005). The solution containing the proteolytic digests was first fractionated in a ionic exchange column.…”

Section: Mass Spectrometry Analysismentioning

confidence: 99%

Photosynthesis, chloroplast ultrastructure, chemical composition and oxidative stress in Theobroma cacao hybrids with the lethal gene Luteus-Pa mutant

Rehem¹,

Almeida²,

Santos³

et al. 2011

Photosynt.

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The Theobroma lethal character Luteus-Pa segregates in a 3:1 ratio, expresses in recessive homozygosis, initially inducing leaf chlorosis and finally provoking seedlings death. The objective of this work was to evaluate gas exchange, chlorophyll fluorescence emission, chemical composition and oxidative stress of wild and mutant seedlings resulting from the crosses Pa 30 × Pa 169 and its reciprocal, aiming to elucidate the seedlings death induced by Luteus-Pa. At 15 day after emergence (DAE) differences began to appear between the wild type and mutant. Mutant seedlings showed: (1) lack of photosynthesis and alterations in chloroplast morphology; (2) lower level of three abundant groups of proteins in leaves; (3) decrease in the content of chloroplastidic pigments (4) decrease in peroxidases activities and increase in leaf polyphenol oxidase activity; (5) decrease in carbohydrate and concentration of some nutrients and low dry mass in all plant parts. In leaves of mutant seedlings of both crosses damages occurred in the system responsible for the photochemical phase of photosynthesis. Variations in growth parameters and subsequent seedling death up to 60 DAE were related to exhaustion of cotyledonary reserves, inactive photosynthetic apparatus and oxidative stress.

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Section: Mass Spectrometry Analysismentioning

confidence: 99%

Photosynthesis, chloroplast ultrastructure, chemical composition and oxidative stress in Theobroma cacao hybrids with the lethal gene Luteus-Pa mutant

Rehem¹,

Almeida²,

Santos³

et al. 2011

Photosynt.

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“…Then a s ðt; t 0 Þ can be described in the laboratory frame by the diagonal components a k ðt À t 0 Þ alongn and a ? ðt À t 0 Þ perpendicular ton [21,23]: a s ðt; t 0 Þ ¼ a k ðt À t 0 ÞnðtÞ#nðt 0 Þ þ a ? ðt À t 0 ÞÎðtÞ#Îðt 0 Þ n þmðt 0 Þ#mðt 0 Þg;…”

Section: Dielectric Memory Effect: An Outline Of the Theorymentioning

confidence: 99%

“…According to the dielectric spectroscopy data [19,20], this switching time is in fact of the same order as t for 5CB, which might suggest that the NLC response is influenced by the dipole relaxation dynamics. Direct evidence came first from the experiments with DFNs [21,22], in which t is long, and thus easier to study. It was demonstrated that when the electric field changes over the time close to t, the instantaneous and 'past' contributions to the dielectric torque can indeed be comparable; moreover, they can cause opposite directions of the director reorientation [21,22].…”

Section: Introductionmentioning

confidence: 98%

“…Direct evidence came first from the experiments with DFNs [21,22], in which t is long, and thus easier to study. It was demonstrated that when the electric field changes over the time close to t, the instantaneous and 'past' contributions to the dielectric torque can indeed be comparable; moreover, they can cause opposite directions of the director reorientation [21,22]. Later, the exploration was extended to conventional LCs such as 5CB [23].…”

Section: Introductionmentioning

confidence: 98%

“…For a detailed description, the reader is referred to the original publications [21][22][23][24][25][26][27]. The article is organised as follows.…”

Section: Introductionmentioning

confidence: 99%

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Dielectric relaxation and memory effects in nematic liquid crystals

Shiyanovskii

Lavrentovich

2010

Liquid Crystals

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Liquid crystals are fluids with anisotropic dielectric properties. Since the 1930s, when dielectric anisotropy was shown by Frederiks and Tsvetkov to cause director reorientation in an applied electric field, deepening our understanding of this property has been a leading theme in the development of liquid crystal science that culminated in the modern liquid crystal displays revolution. Saupe contributed greatly to the field by first coauthoring the molecular statistical theory of the nematic order, and then using it to explain how the nematic order affects dielectric relaxation in liquid crystals, i.e., how the components of the dielectric tensor depend on the frequency of the applied electric field. We review recent developments in the field associated with the finite rate of the dielectric relaxation, which results in a time lag of the electric displacement as compared with the instantaneous value of the electric field. This time lag causes profound effects on director reorientation when the characteristic time of the field change is close to (or smaller than) the dielectric relaxation time. We review recent experimental and theoretical works that link dielectric relaxation in nematic liquid crystals to the dynamics of the director and dielectric heating, and illustrate how the dielectric memory effect features in electro-optics of these materials.

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Red, Green, and Blue Reflections Enabled in an Electrically Tunable Helical Superstructure

Hsiao

Yang

Shen

et al. 2018

Advanced Optical Materials

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reflection of light. The structure of a CLC possesses self-assembled periodicity, with the orientation of the CLC mole cules rotating around a helical axis. Such a configuration can separate light traveling along the helical axis into right-and left-handed circularly polarized components. Circularly polarized light with the same handedness as that of the cholesteric molecule is reflected, whereas the other is transmitted. The selective reflection, also known as the Bragg reflection, is produced in the spectral range in terms of wavelengths λ: Δλ = (n e − n o )P, which is determined by the typically temperature-dependent pitch length P of the CLC helix as well as the birefringence defined as the difference between the extraordinary refractive index n e and the ordinary refractive index n o . The Bragg reflection band is centered at λ 0 = (n e + n o )⋅P/2 for incident light propagating along the cholesteric helix. If the selective reflection band is located in the visible range, the CLC will reflect colors, rendering its iridescent look. The pitch length and, in turn, the reflective wavelengths of light can be varied by stimuli such as electric or magnetic field, heat, [9] and even light, [1,10] facilitating CLC's applications as temperature indicators, [3] biosensors, [11] and general optical devices. [12,13] Recently, light-driven Bragg reflections of CLC materials have been extensively explored. [14,15] Such light-sensitive systems can be achieved by doping photoresponsive chiral or achiral azobenzenes into a CLC host so that the resultant cholesteric phase behavior can be modulated by trans-cis photo isomerization of the azo dopant. Nevertheless, the most desirable and least arduous approach to controlling the reflected light is by applying an electric field to the optical component. Recently, Xiang et al. have shown electrical tuning of selective reflection light from ultraviolet to visible based on an oblique helicoidal cholesteric cell. [16] The dielectric heating effect is the process in which a highfrequency electric field heats a dielectric substance. At high frequencies, this effect is caused by molecular dipole rotation within the dielectric material. Some special liquid crystalline materials such as dual-frequency liquid crystals (DFLCs) exhibit such pronounced effect. As a physical property of DFLCs, a relaxation of the component of dielectric constant parallel to the molecular axis, ε || , takes place at some point (typically of the order of 10 kHz) in the frequency domain, causing ε || to drop and become equal to the component of dielectric constant perpendicular to the molecular axis, ε ⊥ . Consequently, the dielectric anisotropy Δε (ε || − ε ⊥ ) changes its sign from positive to negative beyond the so-called crossover frequency f c . This phenomenon Materials with tunable optical properties in the visible spectrum are intriguingly important in science and technology. Such desired tunability can be conveniently accomplished by controlling optical materials with electric field. Now an organic film...

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Dielectric Torque and Orientation Dynamics of Liquid Crystals with Dielectric Dispersion

Cited by 30 publications

References 11 publications

Photosynthesis, chloroplast ultrastructure, chemical composition and oxidative stress in Theobroma cacao hybrids with the lethal gene Luteus-Pa mutant

Photosynthesis, chloroplast ultrastructure, chemical composition and oxidative stress in Theobroma cacao hybrids with the lethal gene Luteus-Pa mutant

Dielectric relaxation and memory effects in nematic liquid crystals

Red, Green, and Blue Reflections Enabled in an Electrically Tunable Helical Superstructure

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