Effect of spherical magnetic particles on liquid crystals behavior studied by surface acoustic waves

Bury, Peter; Kúdelčík, Jozef; Hardoň, Štefan; Veveričík, Marek; Kopčanský, P.; Τimko, M.; Závišová, V.

doi:10.1016/j.jmmm.2016.09.023

Cited by 18 publications

(10 citation statements)

References 17 publications

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“…The first with relaxation time 9.10 s, indicating very similar process as in the case of magnetic field and second with much longer relaxation time, 94.0 s that can be due to the larger magnetic particles. However, these processes are slower than in the case of spherical particles [12,13]. The experimental observations confirm the role of magnetic particles in LC and their interaction with liquid crystal molecules and coincide with previous results obtained investigating the dielectric behavior of the same LCs [5,6,9].…”

Section: Resultssupporting

confidence: 91%

Structural Changes in Liquid Crystals Doped with Rod-Like Magnetic Particles Studied by Surface Acoustic Waves

et al. 2017

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The effect of rod-like magnetic particles on liquid crystal (6CHBT) structural changes in electric and weak magnetic fields were studied by means of the attenuation of surface acoustic wave of frequency 30 MHz propagating along ferronematic liquid crystals. Three low volume concentrations (Φ = 1 × 10 −5 , 1 × 10 −4 and 1 × 10 −3 ) of rod-like magnetic particles were added to liquid crystal during its isotropic phase. Several measurements including the investigation of the effects of electrical and magnetic fields applied both separately and in conjunction as well as the influence of temperature on the surface acoustic wave attenuation were performed. The distinctive surface acoustic wave attenuation responses induced by both electric and magnetic fields in studied ferronematic liquid crystals have been observed suggesting both structural changes and the orientational coupling between magnetic moments of magnetic particles and the director of the liquid crystal. Obtained results confirmed the significant influence of the presence of magnetic particles on the structural properties and resulting behavior of 6CHBT liquid crystal.

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Section: Resultssupporting

confidence: 91%

Structural Changes in Liquid Crystals Doped with Rod-Like Magnetic Particles Studied by Surface Acoustic Waves

et al. 2017

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“…It is evident that the stronger anchoring in the case of rod-like particles (rigid anchoring) ensures stable magneto-optical responses. It should be noted that while capacitance measurements [23] showed weak anchoring only in the case of spherical magnetic particles and in the case of both chainlike and rod-like particles rigid anchoring, our SAW [19][20][21] and presented magneto-optical measurements indicated similar behaviour for spherical and chain-like particles but different behaviour in the case of rod-like particles. This fact supports rather the conclusion that the rigid anchoring is above all the characteristic property of only rod-like magnetic particles in LC suspension.…”

Section: Resultsmentioning

confidence: 50%

“…The intensity of transmitted light was recorded by means of a photodetector connected to a multimeter and subsequently to the computer that monitored the light intensity as a function of magnetic field. The magnetic field that was controlled also by computer could be increased/decreased continuously (80 mT/min) or altered by a jump (pulsed change) with the relaxation time of the increase/decrease shorter than 0.3 s. The pulse width (duration) 120 s was chosen on the basis of our previous results obtained investigating structural changes in these LCs using surface acoustic waves [19,20,21] when SAW changes could reach the saturated state during such long time. No bias magnetic field was applied before starting the measurement so that suspensions could appear to be compensated ferronematics.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we have studied the effect of magnetic particles on LC structural changes in electric and magnetic fields using the measurement of attenuation of the surface acoustic wave (SAW) propagating along ferronematic liquid crystal. The magnetic nanoparticles in low volume concentration (Φ = 10 −4 -10 −5 ) and a different arrangement, including spherical, rod-like, and chainlike shape, as a dopant in the LC (6CHTB), were investigated [19][20][21]. The structural changes of these ferronematics were studied also by capacitance measurements [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Spherical, Rod-Like and Chain-Like Magnetic Nanoparticles on Magneto-Optical Response of Nematics

et al. 2019

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The effect of magnetic nanoparticles of low concentrations and different shapes, including spherical, rodlike, and chain-like shape on the magneto-optical response of nematic liquid crystal 6CHBT is investigated. The magneto-optical effect was examined using a linearly polarized laser beam (532 nm) passed through liquid crystal cell under both linearly increasing and pulsed magnetic fields. The analysis of observed magneto-optical characteristics and magneto-optical time responses confirmed the role of both concentration and shape of magnetic particles on the resultant magneto-optical behavior concerning both its stability and switching time.

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“…The nominally 5.2 μm diameter Hexcel ® IM7 fibers 44 were woven into five Harness Satin (5HS) fabric (16 ends per inch), yielding 37% (nominal) fiber volume fraction in the finished composite. The preceramic polymer used was allylhydridopolycarbosilane (AHPCS) preceramic polymer, which is commercially available under the tradename StarPCS™ SMP-10.…”

Section: Methodsmentioning

confidence: 99%

A critical review of bioceramics for magnetic hyperthermia

et al. 2021

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Hyperthermia (HT) is a rapid cancer therapy inducing cellular apoptosis by increasing the local temperature of cancerous tissues between 40 and 44°C. 1 The tumors are highly susceptible to this thermal range at which cancerous cells are destroyed, while the normal cells undergo no significant damaging effects. HT is induced by using magnetic materials under an alternating magnetic field (AMF). Benefitting from some favorable characteristics of magnetic nanomaterials (MNPs), magnetic HT has drawn enormous attention and reduced the adverse side effects related to conventional treatments of several tumors such as prostate, glioblastoma, and metastatic bone cancer. 1 This method is usually combined with other therapeutic approaches like chemotherapy (drug delivery), photothermal therapy, gene therapy, immunotherapy, and high-intensity focused ultrasound, which is critically discussed in this paper. 1 The exact process of HT is not yet fully understood since a variety of biological effects can simultaneously occur like heat-induced alteration of cells signaling pathways, DNA, and RNA alterations; expressions of heat-shock proteins; and many other biochemical changes, as well as the direct cytotoxic effect of heat. 2,3 Still, there is a theory which has been mostly accepted by scientists that the impaired vascularization of tumors, together with heat, leads to the lack of oxygen in the tumor environment. As a result, malignant cells escalate their anaerobic metabolism

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Effect of spherical magnetic particles on liquid crystals behavior studied by surface acoustic waves

Cited by 18 publications

References 17 publications

Structural Changes in Liquid Crystals Doped with Rod-Like Magnetic Particles Studied by Surface Acoustic Waves

Structural Changes in Liquid Crystals Doped with Rod-Like Magnetic Particles Studied by Surface Acoustic Waves

Effect of Spherical, Rod-Like and Chain-Like Magnetic Nanoparticles on Magneto-Optical Response of Nematics

A critical review of bioceramics for magnetic hyperthermia

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