Zeitschriftenartikel: „Phase isotrope“

1

Pelzl, Gerhard. „Umwandlung einer nematischen in die isotrope Phase durch photochemische Isomerisierung“. Zeitschrift für Chemie 17, Nr. 8 (01.09.2010): 294–95. http://dx.doi.org/10.1002/zfch.19770170809.

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2

Zou, Peng, und Jiubing Cheng. „Three-dimensional passive-source anisotropic reverse time migration for imaging lithospheric discontinuities“. Geophysical Journal International 226, Nr. 3 (03.06.2021): 2103–15. http://dx.doi.org/10.1093/gji/ggab201.

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SUMMARY The scattered teleseismic body waves have been used intensively to characterize the receiver-side lithospheric structures. The routinely used ray-theory-based methods have limitations to image complex structures and tackle strong heterogeneities. The newly developed wave-equation based, passive-source reverse time migration (RTM) approach can overcome such limitations. To date, passive-source RTM has been developed only for isotropic media. However, at least to the first-order, most lithospheric structures possess effective transverse isotropy with spatially variable symmetry directions. It is important to know the magnitudes of imaging errors that may be introduced by passive-source RTM when seismic anisotropy is treated in an incorrect way. In this paper, we investigate the influence of elastic anisotropy on teleseismic P-to-S conversions at the lithospheric discontinuities and explain why an isotropic RTM may fail to focus the converted wavefields from the perspective of relative arrival time variations with backazimuth and shear wave splitting. Accordingly, we extend the passive-source RTM approach for imaging 3-D lithospheric targets possessing transverse isotropy from the following two aspects: First, the teleseismic recordings with direct P and converted S phases are reverse-time extrapolated using rotated staggered grid (RSG) pseudospectral method, which can tackle strong heterogeneity and transverse isotropies with symmetry axes in arbitrary direction; Secondly, the backward elastic wavefields are efficiently decomposed into vector anisotropic P and S modes to support accurate imaging.

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Chen, Shi-Lin, Zhi-Cheng Ma, Chang-Ling Fan, Yu-Lin Liang und Chong Ye. „Study on spinning stability and microstructure of mesophase pitch“. Materials Express 10, Nr. 10 (31.10.2020): 1711–17. http://dx.doi.org/10.1166/mex.2020.1802.

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The effect of spinning temperature on phase stability, rheological stability, and thermal stability of mesophase pitch (MP), naphthalene-based mesophase pitch (AR) and microstructure of pitch filament were investigated in this study. Results showed that the interface stratification of anisotropic and isotropic phases, local enrichment of isotropic phases and extensive enrichment of isotropic phases existed in the spinning process for mesophase pitch. The local enrichment of isotropic phase was observed in MP and AR at the spinning temperature of 320 °C. The interface stratification of anisotropic and isotropic phases and extensive enrichment of isotropic phases were generated in MP when the spinning temperature reached 340 °C. This phase separation reduced the rheological stability and thermal stability of mesophase pitch and then affected the spinning ability. The inhomogeneous pores were also formed in the MP and AR mesophase pitch filament at the spinning temperature of 340 °C.

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Bailly-Reyre, Aurélien, und Hung T. Diep. „Nematic and Smectic Phases: Dynamics and Phase Transition“. Symmetry 12, Nr. 9 (22.09.2020): 1574. http://dx.doi.org/10.3390/sym12091574.

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We study in this paper the dynamics of molecules leading to the formation of nematic and smectic phases using a mobile 6-state Potts spin model with Monte Carlo simulation. Each Potts state represents a molecular orientation. We show that, with the choice of an appropriate microscopic Hamiltonian describing the interaction between individual molecules modeled by 6-state Potts spins, we obtain the structure of the smectic phase by cooling the molecules from the isotropic phase to low temperatures: molecules are ordered in independent equidistant layers. The isotropic-smectic phase transition is found to have a first-order character. The nematic phase is also obtained with the choice of another microscopic Hamiltonian. The isotropic-nematic phase transition is a second-order one. The real-time dynamics of the molecules leading to the liquid-crystal ordering in each case is shown by a video.

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Reyes, Catherine G., Jörg Baller, Takeaki Araki und Jan P. F. Lagerwall. „Isotropic–isotropic phase separation and spinodal decomposition in liquid crystal–solvent mixtures“. Soft Matter 15, Nr. 30 (2019): 6044–54. http://dx.doi.org/10.1039/c9sm00921c.

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6

Ji, Guangzhong, Pingsong Zhang, Rongxin Wu, Liquan Guo, Zean Hu und Haibo Wu. „Calculation method and characteristic analysis of dispersion curves of Rayleigh channel waves in transversely isotropic media“. GEOPHYSICS 85, Nr. 6 (01.11.2020): C187—C198. http://dx.doi.org/10.1190/geo2019-0345.1.

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Coal seams have beddings and fissures and are typically anisotropic media. Current channel wave theories are mainly based on isotropic media, and few studies exist on the dispersion characteristics of Rayleigh channel waves in anisotropic models, such as transversely isotropic (TI) media. We chose the generalized reflection-transmission coefficient method to solve the dispersion curves of Rayleigh channel waves in TI media. However, it is difficult to solve the associated dispersion equations of Rayleigh channel waves using this method directly. Therefore, we have extended the generalized reflection-transmission coefficient method and determined the improved accuracy through numerical simulation. We analyzed the dispersion characteristics of Rayleigh channel waves of several typical coal seam models in TI media. The results showed that in the three-layer model, the difference in fundamental-mode dispersion curves between vertically transversely isotropic (VTI) media and isotropic media was relatively small; however, the differences in the higher order dispersion curves were slightly larger. The difference in the Airy phase velocity between horizontal transversely isotropic (HTI) and isotropic media was relatively large. When the coefficient of variation in the qP waves ([Formula: see text]) was greater than 0, the fundamental-mode and first-order phase velocity curves of HTI media exhibited an evident intersection at the head end. In the dirt-band-containing coal seam model, within the 350 and 550 Hz band, the high-frequency velocity of fundamental-mode phase velocity curve of isotropy and HTI media was slightly higher than the low-frequency velocity, which is a notable phenomenon.

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Kurbatov, A., A. Drozd-Rzoska, S. J. Rzoska, M. Paluch, P. Malik, J. Zioło und J. Jadżyn. „Universal Scaling of Alpha Relaxation in Complex Liquids“. Zeitschrift für Naturforschung A 56, Nr. 12 (01.12.2001): 893–94. http://dx.doi.org/10.1515/zna-2001-1217.

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Abstract A plot is given, showing the result of a scaling analysis of dielectric loss curves containing, apart from low molecular glass former data (glycerol, dibutyl phtalate), also loss curves of the following liquid crystalline materials, mostly in the iso tropic phase: 4-(2-methylbutyl)-4'cyanobiphenyl (5*CB, supercooled isotropic phase), 4-cyano-4-n-alkyl biphenyls (nematogens 5CB and 8CB, isotropic phase), 4-(4-cyano-4-butylcyclohexyl)-4'-octylbiphenyl (laterally substituted nema-togen, isotropic phase), and 4-n-alkyl-4'-isothiocyanatobiphe-nyl (5 and 10 BT, isotropic and SmE phases). The plot applies the scaling formula originally proposed for glassforming, super cooled liquids [Dendzik et al.7]. The result supports the recent suggestion that dielectric relaxation in the isotropic phase of nematogens may show some features typical for "glassy" mate rials.

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8

Kawakatsu, Hitoshi. „A new fifth parameter for transverse isotropy“. Geophysical Journal International 204, Nr. 1 (01.12.2015): 682–85. http://dx.doi.org/10.1093/gji/ggv479.

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Abstract Properties of a new parameter, ηκ, that is recently introduced by Kawakatsu et al. for transverse isotropy are examined. It is illustrated that the parameter nicely characterizes the incidence angle dependence of bodywave phase velocities for vertical transverse isotropy models that share the same P- and S-wave anisotropy. When existing models of upper-mantle radial anisotropy are compared in terms of this new parameter, PREM shows a distinct property. Within the anisotropic layer of PREM (a depth range of 24.4–220 km), ηκ < 1 in the upper half and ηκ > 1 in the lower half. If ηκ > 1, anisotropy cannot be attributed to a layering of homogeneous isotropic layers, and thus requires the presence of intrinsic anisotropy.

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Gradišek, Anton, Mario Cifelli, Michal Wojcik, Tomaž Apih, Sergey Dvinskikh, Ewa Gorecka und Valentina Domenici. „Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry“. Crystals 9, Nr. 3 (26.03.2019): 178. http://dx.doi.org/10.3390/cryst9030178.

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In this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled 9/2 RS/RS, and a bimesogenic liquid crystal labelled L1, show a direct transition between two isotropic phases followed, at lower temperatures, by the optically isotropic, 3D structured, cubic phase. These systems have been investigated by means of 1H NMR diffusometry and 1H NMR relaxometry in order to characterize their isotropic–isotropic’–cubic mesophase behavior, mainly on the dynamic point of view. In particular, the temperature trend of the self-diffusion coefficients measured for both samples allowed us to significantly distinguish between the two isotropic phases, while the temperature dependence of the 1H spin-lattice relaxation time (T1) did not show significant discontinuities at the isotropic–isotropic’ phase transition. A preliminary analysis of the frequency-dependence of 1H T1 at different temperatures gives information about the main motional processes active in the isotropic mesophases.

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de las Heras, Daniel, und Matthias Schmidt. „Bulk fluid phase behaviour of colloidal platelet–sphere and platelet–polymer mixtures“. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, Nr. 1988 (13.04.2013): 20120259. http://dx.doi.org/10.1098/rsta.2012.0259.

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Using a geometry-based fundamental measure density functional theory, we calculate bulk fluid phase diagrams of colloidal mixtures of vanishingly thin hard circular platelets and hard spheres. We find isotropic–nematic phase separation, with strong broadening of the biphasic region, upon increasing the pressure. In mixtures with large size ratio of platelet and sphere diameters, there is also demixing between two nematic phases with differing platelet concentrations. We formulate a fundamental measure density functional for mixtures of colloidal platelets and freely overlapping spheres, which represent ideal polymers, and use it to obtain phase diagrams. We find that, for low platelet–polymer size ratio, in addition to isotropic–nematic and nematic–nematic phase coexistence, platelet–polymer mixtures also display isotropic–isotropic demixing. By contrast, we do not find isotropic–isotropic demixing in hard-core platelet–sphere mixtures for the size ratios considered.

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Straughan, B. „Horizontally isotropic double porosity convection“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, Nr. 2221 (Januar 2019): 20180672. http://dx.doi.org/10.1098/rspa.2018.0672.

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We analyse instability and nonlinear stability in a layer of saturated double porosity medium. In a double porosity or bidisperse porous medium, there are normal pores which give rise to a macroporosity. But, there are also cracks or fissures in the solid skeleton and these give arise to another porosity known as micro porosity. In this paper, the macropermeability is horizontally isotropic, in the sense that the vertical component of permeability is different to the horizontal one which is the same in all horizontal directions. Thus, the permeability is transversely isotropic with the isotropy axis in the vertical direction of gravity. We also allow the micro permeability to be horizontally isotropic, but the permeability ratios of vertical to horizontal are different in the macro- and micro-phases. The effect of the difference of ratios is examined in detail.

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Centore, Roberto, Valeria Capitolino, Francesca Cerciello, Angela Tuzi, Fabio Borbone, Antonio Carella und Antonio Roviello. „A topotactic transition in a liquid crystal compound“. CrystEngComm 17, Nr. 46 (2015): 8864–69. http://dx.doi.org/10.1039/c5ce00660k.

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The title compound has two crystal phases related by an enantiotropic single-crystal-to-single-crystal transition and a nematic liquid crystalline phase before transition to the isotropic liquid phase.

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13

Dvorak, G. J. „Thermal Expansion of Elastic-Plastic Composite Materials“. Journal of Applied Mechanics 53, Nr. 4 (01.12.1986): 737–43. http://dx.doi.org/10.1115/1.3171852.

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Exact relationships are derived between instantaneous overall thermal stress or strain vectors and instantaneous overall mechanical stiffness or compliance, for two binary composite systems in which one of the phases may deform plastically. Also, the local instantaneous thermal strain and stress concentration factors are related in an exact way to the corresponding mechanical concentration factors. The results depend on instantaneous thermoelastic constants and volume fractions of the phases. They are found for fibrous composites with two distinct elastically isotropic or transversely isotropic phases, and for any binary composite with elastically isotropic phases. The results indicate that in the plastic range the thermal and mechanical loading effects are coupled even if the phase properties do not depend on changes in temperature. The derivation is based on a novel decomposition procedure which shows that spatially uniform elastic strain fields can be created in certain heterogeneous media by superposition of uniform phase eigenstrains with local strains, caused by piecewise uniform stress fields which are in equilibrium with prescribed surface tractions. The method is extended to discretized microstructures, and also to the analysis of moisture absorption and phase transformation effects on overall response and on local fields in the two composite materials.

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Urban, Stanisław, Bo Gestbloma, Roman Dąbrowskib und Jerzy Dziaduszekb. „Study of High Frequency Relaxation Processes in Three Substances with the -CN Groups at the Lateral Positions“. Zeitschrift für Naturforschung A 55, Nr. 8 (01.08.2000): 733–40. http://dx.doi.org/10.1515/zna-2000-0810.

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Abstract Three liquid crystalline (LC) substances with the cyano-groups attached at the lateral positions to the molecular cores were studied with the aid of dielectric spectroscopy methods. The high frequency relaxation process connected with the molecular reorientations around the long molecular axes was studied in the isotropic, nematic and several smectic phases. The dielectric spectra are rather complex, indicating a contribution from several molecular processes to the main relaxation process. The dielectric time changes smoothly at the phase transitions between "liquid-like" phases (isotropic -nematic -smectic A -smectic C), and becomes shorter at the transition to the "solid-like" smectic G phase with a low-ering of the activation barrier. This indicates that the molecules perform broad angle librational motions rather than overall rotational motions in this phase. In case of a substance having two cyano groups at-tached to the benzene ring, a pronounced jump-wise change of the relaxation time was observed at the isotropic -smectic A transition.

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Rahman, Md Asiqur, Itaru Yamana, Yeap Guan Yeow, Suhana Binti Mohd Said und Munehiro Kimura. „Electro-Optic Potential of Room and High Temperature Polymer Stabilised Blue Phase Liquid Crystal“. Advanced Materials Research 895 (Februar 2014): 186–89. http://dx.doi.org/10.4028/www.scientific.net/amr.895.186.

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In the field of liquid crystals, blue phases (BPs) are one of the most unique and interesting sub-phases. Blue-phase liquid crystal holds the potential to become next-generation display and photonics device because of its sub-millisecond gray-to-gray response time, alignment-layer-free process, optically isotropic dark state, and cell gap insensitivity. The BPLC is a highly chiral liquid crystal system possessing crystal like unit cell structure and exist over a small temperature range (0.5-2 °C) between isotropic and chiral nematic (N*) thermotropic phase. The narrow phase range has been an intrinsic problem for blue phase, and a useful strategy of widening the phase is by adding polymer to form a polymer stabilised blue phase liquid crystal. In this paper, we demonstrate polymer stabilization using two different cases: a room temperature mixture containing E8, PE-5CNF and CPP-3FF, and a high temperature mixture using a single molecule blue phase liquid crystal material, TCB5. Comparison of the polymer stabilization effects on these two cases will be discussed, in the perspective of their potential in electro-optic applications.

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Sandmann, M., F. Hamann und A. Würflinger. „PVT Measurements on 4-n-Pentyl-4´-Cyano-Biphenyl (5CB) and trans-4-(4´-Octyl-Cyclohexyl)-Benzonitrile (8PCH) up to 300 MPa“. Zeitschrift für Naturforschung A 52, Nr. 10 (01.10.1997): 739–47. http://dx.doi.org/10.1515/zna-1997-1008.

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Abstract Specific volumes are presented for 4-n-pentyl-4´-cyanobiphenyl (5CB) and trans-4-(4´-octyl-cyclo-hexyl)-benzonitrile (8PCH) for temperatures between 300 and 370 K up to 300 MPa. The p,Vm ,T data were determined for the liquid crystalline and isotropic phases, and partly also for the solid phase adjacent to the melting curve. Stable and metastable crystal phases can be distinguished. The density and melting temperature of the metastable form are lower than for the stable one. Volume and enthalpy changes accompanying the phase transitions are reported as well. The p,Vm ,T data allow to calculate the entropy change for a hypothetical transition at constant volume. The molar volumes along the nematic-isotropic phase transition TNI (p) allow to determine the molecular field parameter γ = ∂In TNI /∂ In VNI.

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Kim, Eugene H., G. Fáth, J. Sólyom und D. J. Scalapino. „Phase transitions between topologically distinct gapped phases in isotropic spin ladders“. Physical Review B 62, Nr. 22 (01.12.2000): 14965–74. http://dx.doi.org/10.1103/physrevb.62.14965.

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18

Aleshin, V. I. „Elastic properties of two-dimensional two-phase composites with isotropic phases“. Mechanics of Composite Materials 46, Nr. 5 (17.11.2010): 513–30. http://dx.doi.org/10.1007/s11029-010-9168-4.

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19

Sharma, Abhishek K., Vikram Thapar und Fernando A. Escobedo. „Solid-phase nucleation free-energy barriers in truncated cubes: interplay of localized orientational order and facet alignment“. Soft Matter 14, Nr. 11 (2018): 1996–2005. http://dx.doi.org/10.1039/c7sm02377d.

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20

Barbosa, Gustavo Coqui, Luciano Pessanha Moreira, Lílian Barros da Silveira und Marcelo Costa Cardoso. „Micromechanical Modeling of DP600 and DP800 Steels Plastic Behavior Based on the Mori-Tanaka Homogenization Method“. Materials Science Forum 930 (September 2018): 311–16. http://dx.doi.org/10.4028/www.scientific.net/msf.930.311.

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The properties of the dual-phase steels are attributed to the chemical composition, type, size, amount, and spatial distribution of different phases that can be obtained during thermomechanical treatments. In this way, modeling of the mechanical behavior of the dual-phase steel constituents, namely, ferrite and martensite, is crucial to the numerical simulation of sheet metal forming processes mainly to forecast the residual stresses per phase. In this work, the microstructure of as-received DP600 and DP800 cold rolled steel sheets with 1.2 mm nominal thickness were firstly characterized by means of scanning electron microscopy technique. The grain sizes and volume fractions of ferrite and martensite phases were obtained by means of digital image analysis. The Mori-Tanaka homogenization scheme was implemented in the finite element code ABAQUS assuming linear isotropic elasticity and isotropic work-hardening behavior for both ferrite (matrix) and martensite (inclusion) phases. The numerical predictions obtained with the Mori-Tanaka homogenization scheme for the macroscopic uniaxial tensile behavior are in good agreement with the experimental curves of both dual-phase steels.

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Ferreiro-Córdova, Claudia, C. Patrick Royall und Jeroen S. van Duijneveldt. „Anisotropic viscoelastic phase separation in polydisperse hard rods leads to nonsticky gelation“. Proceedings of the National Academy of Sciences 117, Nr. 7 (31.01.2020): 3415–20. http://dx.doi.org/10.1073/pnas.1909357117.

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Spinodal demixing into two phases having very different viscosities leads to viscoelastic networks—i.e., gels—usually as a result of attractive particle interactions. Here, however, we demonstrate demixing in a colloidal system of polydisperse, rod-like clay particles that is driven by particle repulsions instead. One of the phases is a nematic liquid crystal with a highly anisotropic viscosity, allowing flow along the director, but suppressing it in other directions. This phase coexists with a dilute isotropic phase. Real-space analysis and molecular-dynamics simulations both reveal a long-lived network structure that is locally anisotropic, yet macroscopically isotropic. We show that our system exhibits the characteristics of colloidal gelation, leading to nonsticky gels.

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Davidson, Patrick, Christophe Penisson, Doru Constantin und Jean-Christophe P. Gabriel. „Isotropic, nematic, and lamellar phases in colloidal suspensions of nanosheets“. Proceedings of the National Academy of Sciences 115, Nr. 26 (11.06.2018): 6662–67. http://dx.doi.org/10.1073/pnas.1802692115.

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The phase diagram of colloidal suspensions of electrically charged nanosheets, such as clays, despite their many industrial uses, is not yet understood either experimentally or theoretically. When the nanosheet diameter is very large (∼100 nm to 1 µm), it is quite challenging to distinguish the lamellar liquid-crystalline phase from a nematic phase with strong stacking local order, often called “columnar” nematic. We show here that newly upgraded small-angle X-ray scattering beamlines at synchrotron radiation facilities provide high-resolution measurements which allow us to identify both phases unambiguously, provided that single domains can be obtained. We investigated dilute aqueous suspensions of synthetic Sb3P2O143−nanosheets that self-organize into two distinct liquid-crystalline phases, sometimes coexisting in the same sample. Close examination of their X-ray reflection profiles in the directions perpendicular to the director demonstrates that these two mesophases are a columnar nematic and a lamellar phase. In the latter, the domain size reaches up to ∼20 µm, which means that each layer is made of >600 nanosheets. Because the lamellar phase was only rarely predicted in suspensions of charged disks, our results show that these systems should be revisited by theory or simulations. The unexpected stability of the lamellar phase also suggests that the rims and faces of Sb3P2O143−nanosheets may have different properties, giving them a patchy particle character.

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Beetle, Christopher, Jonathan S. Engle, Matthew E. Hogan und Phillip Mendonça. „Diffeomorphism invariant cosmological symmetry in full quantum gravity“. International Journal of Modern Physics D 25, Nr. 08 (Juli 2016): 1642012. http://dx.doi.org/10.1142/s0218271816420128.

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This paper summarizes a new proposal to define rigorously a sector of loop quantum gravity at the diffeomorphism invariant level corresponding to homogeneous and isotropic cosmologies, thereby enabling a detailed comparison of results in loop quantum gravity and loop quantum cosmology. The key technical steps we have completed are (a) to formulate conditions for homogeneity and isotropy in a diffeomorphism covariant way on the classical phase-space of general relativity, and (b) to translate these conditions consistently using well-understood techniques to loop quantum gravity. Some additional steps, such as constructing a specific embedding of the Hilbert space of loop quantum cosmology into a space of (distributional) states in the full theory, remain incomplete. However, we also describe, as a proof of concept, a complete analysis of an analogous embedding of homogeneous and isotropic loop quantum cosmology into the quantum Bianchi I model of Ashtekar and Wilson-Ewing. Details will appear in a pair of forthcoming papers.

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Workentin, Mark S., Brian J. Fahie und William J. Leigh. „Photochemical probes of conformational mobility in liquid crystals. The photochemistry of β-phenyl-4-methoxypropiophenone in the nematic and smectic B phases of CCH-n and OS-nm liquid crystals“. Canadian Journal of Chemistry 69, Nr. 9 (01.09.1991): 1435–44. http://dx.doi.org/10.1139/v91-212.

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The photochemistry of β-phenyl-4-methoxypropiophenone (1) in the isotropic and liquid crystalline (nematic and smectic B) phases of trans, trans-4′-alkyl-(1,1′-bicyclohexyl)-4-carbonitrile (CCH-n) and trans-4-alkylcyclohexyl-trans-4′-alkylcyclohexylcarboxylate (OS-nm) mesogens has been investigated using nanosecond laser flash photolysis techniques. Solubility limits of 1 as a function of temperature in the smectic phases have been rigorously determined by 2H NMR spectroscopy, using α-, methoxy-, and β-phenyl-deuterated analogs of the ketone. Triplet decay of 1 in the smectic (Crystal B) phase of CCH-4 is multiexponential, suggesting that the ketone is solubilized in a distribution of conformations in the highly-ordered liquid crystalline lattice. The average triplet lifetime of 1 at various temperatures throughout the smectic phase is about a factor of three longer than that in homologous nematic and isotropic phases at the same temperature. The differences in the Arrhenius parameters for triplet decay in the smectic and nematic/isotropic phases are very small, however. The present results for 1 in the smectic phase of the CCH-n mesogens correct the interpretation of previously reported data obtained with higher concentration mixtures, and afford an accurate indication of the true effects of smectic B liquid crystalline order on the conformation-dependent triplet state behavior of this molecule. In OS-nm liquid crystals, triplet decay follows clean first order kinetics in all phases, but the variations in Arrhenius dependence with solvent phase are similar to those observed in the CCH-n liquid crystals. Key words: smectic, liquid crystals, 2H NMR, nanosecond laser flash photolysis, intramolecular triplet quenching, photochemistry.

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Chattopadhyay, A., A. K. Verma, M. S. Chaki und A. K. Singh. „Influence of Rigid, Stress-Free and Yielding Base of a Composite Structure on the Propagation of Rayleigh-Type Wave: A Comparative Approach“. Journal of Mechanics 34, Nr. 6 (24.08.2017): 733–48. http://dx.doi.org/10.1017/jmech.2017.65.

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AbstractIn this paper, case wise studies have been made to investigate the possibility of propagation of Rayleigh-type wave in a composite structure comprised of two transversely-isotropic material layers with viscoelastic effect. The common interface between the layers is considered to be rigid whereas the base has been considered as rigid, stress-free and yielding in three different cases (Case-I, II and III). Closed-form of frequency equation and damped velocity equation has been established analytically for propagation of Rayleigh-type wave in a composite structure for all three cases. In special cases, frequency equations and damped velocity equations for the case of composite structure with rigid, stress-free and yielding base have been found in well-agreement to the established standard results pre-existing in the literature. Numerical and graphical computation of phase and damped velocity of Rayleigh-type wave propagating in the composite structure comprised of double transversely-isotropic viscoelastic Taylor sandstone material layers (Model-I) and double isotropic viscoelastic material layers (Model-II) have been carried out. Significant effect of anisotropy and width ratio of layers, dilatational and volume viscoelasticity associated with viscoelasticity of layer medium and yielding parameter associated with yielding base of composite structure on phase and damped velocities of Rayleigh-type wave for the considered models have been traced out. The comparative study has been performed to unravel the effect of viscoelasticity over elasticity and anisotropy over isotropy in the present problem.

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Jadżyn, J., C. Legrand, P. Kędziora, B. Żywucki, G. Czechowski und D. Bauman. „Dielectric Behaviour of 1-(4-Isothiocyanatophenyl)-2-(4-hexyl- bicyclo[2,2,2]octane-1)ethane in Nematic and Isotropic Phases“. Zeitschrift für Naturforschung A 51, Nr. 8 (01.08.1996): 933–38. http://dx.doi.org/10.1515/zna-1996-0808.

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Abstract Static and dynamic investigations of the dielectric properties of the liquid crystal 1-(4-isothio-cyanatophenyl)-2-(4-hexyl-bicyclo[2,2,2]octane-1)ethane in the nematic and isotropic phases have been carried out in the frequency region from 1 kHz to 1 GHz. Two relaxation processes, described by the Debye functions, have been observed not only in the isotropic but also in the nematic phase, when the measurements of the electric permittivity vs. frequency have been made parallel to the orientation axis of liquid crystal. These processes are related to the rotation of the permanent dipole moment around two main molecular axes. The height of the potential barrier which hinders the rotation of the liquid crystal molecule around the short axis in the ordered nematic phase and the order parameter of the liquid crystal investigated have been estimated on the basis of the relaxation time values in the nematic and isotropic phases.

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Drozd-Rzoska, Aleksandra. „‘Quasi-Tricritical’ and Glassy Dielectric Properties of a Nematic Liquid Crystalline Material“. Crystals 10, Nr. 4 (13.04.2020): 297. http://dx.doi.org/10.3390/cryst10040297.

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Results of dielectric studies in the nematic and isotropic liquid phases of pentylcyanobiphenyl (5CB), a model rod-like liquid crystalline material, are shown. They are based on the discussion of the evolution of dielectric constant ( ε ), its changes under the strong electric field (nonlinear dielectric effect, NDE), and finally, the primary relaxation time. It is shown that changes in ε T and NDE are entirely dominated by the impact of pretransitional fluctuations (pre-nematic and pre-isotropic, respectively) which are associated with the weakly discontinuous character of the isotropic–nematic phase transition. This influence also extends for the low-frequency, ionic species dominated, region. Notable, that the derivative-based and distortions sensitive analysis revealed the tricritical nature of the I-N transition. Although the glass transition in 5CB occurs in the deeply supercooled state at T g ≈ − 68 ° C , the dynamics (changes of the primary relaxation time) follow a previtreous pattern both in the isotropic and in the nematic phase. Finally, the discussion of the ’molecular’ vs. ‘quasi-critical’ characterizations of the isotropic and nematic phases is presented. It shows the evident prevalence of the ‘quasi-critical-picture’, which offers the consistent temperature parameterization in the total tested temperature range.

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Jadżyn, J., R. Dąbrowski, K. Glumiak und G. Czechowski. „Shear Viscosity of the Homologous Series of wCHBT (n = 0 ÷ f 12) in the Isotropic and Nematic Phases“. Zeitschrift für Naturforschung A 55, Nr. 6-7 (01.07.2000): 637–40. http://dx.doi.org/10.1515/zna-2000-6-712.

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Abstract The paper presents results of shear viscosity measurements performed on nematogenic 4-(trans-4'-n-alkylcyclohexyl)isothiocyanatobenzenes (CnH 2n + 1-CyHx-Ph-N=C=S, /nCHBT) in the isotropic (n = 0 ÷ 12) and nematic (« = 4 ÷ 12) phases. The viscosity measured in the nematic phase is, due to the flow alignment phenomenon, close to the Migsowicz T? 2 viscosity coefficient. An odd-even effect in the n dependence of the viscosity-activation energy is observed both in the nematic and isotropic phases of nCHBT.

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Zhou, Hongbo, und George A. McMechan. „Analytic study of the geometrical spreading of P-waves in a layered transversely isotropic medium with a vertical symmetry axis“. GEOPHYSICS 65, Nr. 4 (Juli 2000): 1305–15. http://dx.doi.org/10.1190/1.1444822.

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An analytical formula for geometrical spreading is derived for a horizontally layered transversely isotropic medium with a vertical symmetry axis (VTI). With this expression, geometrical spreading can be determined using only the anisotropy parameters in the first layer, the traveltime derivatives, and the source‐receiver offset. Explicit, numerically feasible expressions for geometrical spreading are obtained for special cases of transverse isotropy (weak anisotropy and elliptic anisotropy). Geometrical spreading can be calculated for transversly isotropic (TI) media by using picked traveltimes of primary nonhyperbolic P-wave reflections without having to know the actual parameters in the deeper subsurface; no ray tracing is needed. Synthetic examples verify the algorithm and show that it is numerically feasible for calculation of geometrical spreading. For media with a few (4–5) layers, relative errors in the computed geometrical spreading remain less than 0.5% for offset/depth ratios less than 1.0. Errors that change with offset are attributed to inaccuracy in the expression used for nonhyberbolic moveout. Geometrical spreading is most sensitive to errors in NMO velocity, followed by errors in zero‐offset reflection time, followed by errors in anisotropy of the surface layer. New relations between group and phase velocities and between group and phase angles are shown in appendices.

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Milton, Graeme W., und Andrej V. Cherkaev. „Which Elasticity Tensors are Realizable?“ Journal of Engineering Materials and Technology 117, Nr. 4 (01.10.1995): 483–93. http://dx.doi.org/10.1115/1.2804743.

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It is shown that any given positive definite fourth order tensor satisfying the usual symmetries of elasticity tensors can be realized as the effective elasticity tensor of a two-phase composite comprised of a sufficiently compliant isotropic phase and a sufficiently rigid isotropic phase configured in an suitable microstructure. The building blocks for constructing this composite are what we call extremal materials. These are composites of the two phases which are extremely stiff to a set of arbitrary given stresses and, at the same time, are extremely compliant to any orthogonal stress. An appropriately chosen subset of the extremal materials are layered together to form the composite with elasticity tensor matching the given tensor.

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Abbas, G., und K. Majeed. „Isotropic Gravastar Model in Rastall Gravity“. Advances in Astronomy 2020 (16.11.2020): 1–10. http://dx.doi.org/10.1155/2020/8861168.

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In the present paper, we have introduced a new model of gravastar with an isotropic matter distribution in Rastall gravity by the Mazur–Mottola (2004) mechanism. Mazur–Mottola approach is about the construction of gravastar which is predicted as an alternative to black hole. By following this convention, we define gravastar in the form of three phases. The first one is an interior phase which has negative density; the second part consists of thin shell comprising ultrarelativistic stiff fluid for which we have discussed the length, energy, and entropy. By the graphical analysis of entropy, we have shown that our proposed thin shell gravastar model is potentially stable. The third phase of gravastar is defined by the exterior Schwarzschild geometry. For the interior of gravastar, we have found the analytical solutions free from any singularity and the event horizon in the framework of Rastall gravity.

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32

Huang, Yuan Ming, Qing Lan Ma und Bao Gai Zhai. „Effects of Cyclic Heating and Cooling on the Banana-Phase Growing Behaviors of Banana-Shaped Liquid Crystal 1,3-Phenylene-bis[4-(4-octyl phenylimino)methyl]benzoate“. Key Engineering Materials 428-429 (Januar 2010): 322–25. http://dx.doi.org/10.4028/www.scientific.net/kem.428-429.322.

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The effects of cyclic heating and cooling on the banana-phase growth behaviors of the prototype banana-shaped liquid crystal 1,3-phenylene-bis[4-(4-octylphenylimino)methyl]benzoate were investigated with differential scanning calorimetry and polarized optical microscopy, respectively. Cyclic heating and cooling can reduce the phase transition temperatures and increase the domain sizes of the banana phases of the banana-shaped liquid crystal. These results can be interpreted in terms of the nucleation and growth of the banana phases out of its isotropic phase of the banana-shaped liquid crystal.

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PODIO-GUIDUGLI, PAOLO, und GIORGIO VERGARA CAFFARELLI. „EQUILIBRIUM PHASES AND LAYERED PHASE MIXTURES IN ELASTICITY“. Mathematical Models and Methods in Applied Sciences 02, Nr. 02 (Juni 1992): 143–66. http://dx.doi.org/10.1142/s0218202592000107.

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In this paper an equilibrium phase is a restriction of a piecewise-affine deformation of a body to a (maximal, connected) subbody whose deformation is affine; a layered phase mixture is a continuous deformation that admits at least two distinct phases, separated by a plane interface. We study equilibrium phases and layered phase mixtures in the context of finite elasticity, in the presence of three different boundary conditions of traction: uniform pressure, and two other of null Lagrangians. In Part I we reduce to a unique format the stationarity condition for the existence of equilibrium phases — of the conformal, transversely symmetric and asymmetric types — in elastic materials of arbitrary mechanical response; and we determine reasonable assumptions under which the stationary points of a (generalized) free energy are indeed equilibrium phases. In Part II we restrict attention to isotropic material, and give explicit stationarity and compatibility conditions for the existence of mixtures of two layered, transversely symmetric phases.

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Dlouhý, Ondřej, Václav Karlický, Rameez Arshad, Ottó Zsiros, Ildikó Domonkos, Irena Kurasová, András F. Wacha et al. „Lipid Polymorphism of the Subchloroplast—Granum and Stroma Thylakoid Membrane–Particles. II. Structure and Functions“. Cells 10, Nr. 9 (09.09.2021): 2363. http://dx.doi.org/10.3390/cells10092363.

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In Part I, by using 31P-NMR spectroscopy, we have shown that isolated granum and stroma thylakoid membranes (TMs), in addition to the bilayer, display two isotropic phases and an inverted hexagonal (HII) phase; saturation transfer experiments and selective effects of lipase and thermal treatments have shown that these phases arise from distinct, yet interconnectable structural entities. To obtain information on the functional roles and origin of the different lipid phases, here we performed spectroscopic measurements and inspected the ultrastructure of these TM fragments. Circular dichroism, 77 K fluorescence emission spectroscopy, and variable chlorophyll-a fluorescence measurements revealed only minor lipase- or thermally induced changes in the photosynthetic machinery. Electrochromic absorbance transients showed that the TM fragments were re-sealed, and the vesicles largely retained their impermeabilities after lipase treatments—in line with the low susceptibility of the bilayer against the same treatment, as reflected by our 31P-NMR spectroscopy. Signatures of HII-phase could not be discerned with small-angle X-ray scattering—but traces of HII structures, without long-range order, were found by freeze-fracture electron microscopy (FF-EM) and cryo-electron tomography (CET). EM and CET images also revealed the presence of small vesicles and fusion of membrane particles, which might account for one of the isotropic phases. Interaction of VDE (violaxanthin de-epoxidase, detected by Western blot technique in both membrane fragments) with TM lipids might account for the other isotropic phase. In general, non-bilayer lipids are proposed to play role in the self-assembly of the highly organized yet dynamic TM network in chloroplasts.

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Thiesset, F., L. Danaila und R. A. Antonia. „Dynamical effect of the total strain induced by the coherent motion on local isotropy in a wake“. Journal of Fluid Mechanics 720 (27.02.2013): 393–423. http://dx.doi.org/10.1017/jfm.2013.11.

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AbstractWe assess the extent to which local isotropy (LI) holds in a wake flow for different initial conditions, which may be geometrical (the shape of the bluff body which creates the wake) and hydrodynamical (the Reynolds number), as a function of the dynamical effects of the large-scale forcing (the mean strain, $ \overline{S} $, combined with the strain induced by the coherent motion, $\tilde {S} $). LI is appraised through either classical kinematic tests or phenomenological approaches. In this respect, we reanalyse existing LI criteria and formulate a new isotropy criterion based on the ratio between the turbulence strain intensity and the total strain ($ \overline{S} + \tilde {S} $). These criteria involve either time-averaged or phase-averaged quantities, thus providing a deeper insight into the dynamical aspect of these flows. They are tested using hot wire data in the intermediate wake of five types of obstacles (a circular cylinder, a square cylinder, a screen cylinder, a normal plate and a screen strip). We show that in the presence of an organized motion, isotropy is not an adequate assumption for the large scales but may be satisfied over a range of scales extending from the smallest dissipative scale up to a scale which depends on the total strain rate that characterizes the flow. The local value of this scale depends on the particular nature of the wake and the phase of the coherent motion. The square cylinder wake is the closest to isotropy whereas the least locally isotropic flow is the screen strip wake. For locations away from the axis, the study is restricted to the circular cylinder only and reveals that LI holds at scales smaller than those that apply at the wake centreline. Arguments based on self-similarity show that in the far wake, the strength of the coherent motion decays at the same rate as that of the turbulent motion. This implies the persistence of the same degree of anisotropy far downstream, independently of the scale at which anisotropy is tested.

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Sandmann, M., und A. Würflinger. „PVT Measurements on 4'-w-Hexyl-Biphenyl-4-Carbonitrile (6CB) and 4'-w-Heptyl-Biphenyl-4-Carbonitrile (7CB) up to 300 MPa“. Zeitschrift für Naturforschung A 53, Nr. 5 (01.05.1998): 233–38. http://dx.doi.org/10.1515/zna-1998-0520.

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Abstract P, Vm , T data were established for 4'-n-hexyl-biphenyl-4-carbonitrile (6CB) and 4'-n-heptyl-biphenyl-4-carbonitrile (7CB) between 300 and 370 K up to 300 MPa, and specific volumes were determined for the liquid crystalline, isotropic, and also partly for the crystal phases. Volume and enthalpy changes at the phase transitions are also presented. In the case of 6CB, a new crystal phase has been detected, corresponding to a triple point at 338 K and 196 MPa. The p, Vm , T data enabled us to separate the entropy change into a volume-dependent part and configurational part. From the molar volumes along the nematic-isotropic phase transition TNl(p), the molecular field parameter γ=∂lnTNI/∂lnVNI was determined.

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Pisipati, V. G. K. M., N. V. S. Rao, P. V. Datta Prasad und P. R. Alapati. „Density, Refractive Index and Ultrasonic Velocity Studies Involving N-(p-n-Pentyloxybenzylidene)-p-n-octylaniline“. Zeitschrift für Naturforschung A 40, Nr. 5 (01.05.1985): 472–75. http://dx.doi.org/10.1515/zna-1985-0509.

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The density, refractive index and ultrasonic velocity dependence on temperature for N-(p-npentyloxybenzylidene)- p-n-octylaniline, 50.8, is presented. The compound 50.8 exhibits smectic-B, smectic-A and nematic phases between the solid and isotropic liquid phases. The nematic-isotropic and smectic A-smectic B phase transformations are found to be first order. The interesting smectic A - nematic transformation is confirmed from the results to be second order, although the thermal expansion coefficient and reported enthalpy data had suggested a weak first order transition. The computed adiabatic compressibility, βad, molar sound velocity, Rn, and molar compressibility Aw are presented.

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SURESH, K. A., YUSHAN SHI, A. BHATTACHARYYA und SATYENDRA KUMAR. „WETTING–DEWETTING TRANSITION AND CONFORMAL TO NON-CONFORMAL INTERFACIAL ROUGHNESS TRANSITION IN ULTRA-THIN LIQUID CRYSTAL FILMS ON SOLID SUBSTRATES“. Modern Physics Letters B 15, Nr. 08 (10.04.2001): 225–33. http://dx.doi.org/10.1142/s0217984901001628.

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High-resolution X-ray reflectivity has been employed to study the structure, wetting properties, and interfacial roughness of ultra-thin liquid crystal films. The films were prepared at the air–water interface and transferred on to glass substrates by a modified horizontal deposition technique. A 3-layer film was found to partially-wet the substrate in the nematic and isotropic phases and dewet upon cooling to the crystalline phase. The surface roughnesses at the air-film and the film-glass interfaces exhibited a gradual reversible but hysteretic conformal (strongly correlated) to non-conformal transition between the isotropic and smectic-A phases.

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Matsuyama, Akihiko. „Volume Phase Transitions of Heliconical Cholesteric Gels under an External Field along the Helix Axis“. Gels 6, Nr. 4 (16.11.2020): 40. http://dx.doi.org/10.3390/gels6040040.

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We present a mean field theory to describe cholesteric elastomers and gels under an external field, such as an electric or a magnetic field, along the helix axis of a cholesteric phase. We study the deformations and volume phase transitions of cholesteric gels as a function of the external field and temperature. Our theory predicts the phase transitions between isotropic (I), nematic (N), and heliconical cholesteric (ChH) phases and the deformations of the elastomers at these phase transition temperatures. We also find volume phase transitions at the I−ChH and the N−ChH phase transitions.

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Šilhavý, M. „Phase equilibria in isotropic solids“. Continuum Mechanics and Thermodynamics 25, Nr. 6 (21.11.2012): 795–802. http://dx.doi.org/10.1007/s00161-012-0282-5.

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41

Chen, Dai-Heng. „Crack in Isotropic Phase Joined to Anisotropic Phase.“ Transactions of the Japan Society of Mechanical Engineers Series A 61, Nr. 587 (1995): 1518–24. http://dx.doi.org/10.1299/kikaia.61.1518.

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42

Wang, Ru Zheng, Jian Jun Liu und Hui Li Li. „Study of Blue-Phase III–Isotropic Phase Transition“. Solid State Phenomena 181-182 (November 2011): 71–74. http://dx.doi.org/10.4028/www.scientific.net/ssp.181-182.71.

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In this paper, using the theories of Bogolyubov-Hellman-Feynman (BHF) and mean-spherical approximation, we get the system free energy within the four-order self-consistent cumulant expansion. According to the conditions of equilibrium state and self-consistent equation, we obtain the relation between reduced temperature and inverse correlation length and disscuss that the cubic invariant item is important in explaining BPIII to isotropic transition.

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Urban, S., B. Gestblom, T. Brückert und A. Würflinger. „Study of the Dielectric Properties of 7PCH (4 -(trans -4 -Heptyl-Cyclohexyl)-benzonitrile)“. Zeitschrift für Naturforschung A 50, Nr. 11 (01.11.1995): 984–90. http://dx.doi.org/10.1515/zna-1995-1102.

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Abstract The results of dielectric studies of 7PCH (4-(trans-4-heptyl-cyclohexyl)-benzonitrile) in the nematic and isotropic phases are presented. The complex dielectric permittivity, ε*=ε' - i ε", was measured in the frequency range 1 kHz-5 GHz, with the use of an impedance analyzer and a time domain spectroscopy (TDS) set-up. The relaxation times: longitudinal tII, and transverse t^ in the nematic phase, and tis in the isotropic phase, were obtained. They served for calculation of the activation barriers for different molecular rotation processes occurring in both phases. Additionally, the retardation factors g II and g^ were calculated. Two theoretical models (Meier-Saupe and Coffey et al.) were applied for tne calculation of the nematic potential q. A critical analysis of accessible literature data on the order parameter S is given. On that basis the relation q - SS is tested. The obtained values of the strength parameter S are lower for 7PCH than for 5PCH. Possible contributions to the total energy barrier hindering the molecular rotation around the short axis in the nematic phase are considered.

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Mukherjee, Prabir K. „Dielectric permittivity in the isotropic phase above the isotropic to smectic-A phase transition“. Physics Letters A 377, Nr. 37 (November 2013): 2436–39. http://dx.doi.org/10.1016/j.physleta.2013.07.028.

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Schrijver, P. De, W. Van Dael und J. Thoen. „Surface-induced pretransitional order in the isotropic phase near the isotropic-nematic phase transition“. Liquid Crystals 21, Nr. 5 (November 1996): 745–49. http://dx.doi.org/10.1080/02678299608032886.

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Mukherjee, Prabir K., Sumanta Chakraborty und Sylwester J. Rzoska. „Non-linear dielectric effect in the isotropic phase above the isotropic–cholesteric phase transition“. Chemical Physics 389, Nr. 1-3 (November 2011): 64–67. http://dx.doi.org/10.1016/j.chemphys.2011.08.001.

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Bentley, J. „EFTEM Elemental Mapping of α-α′ Interconnected Isotropic Nanostructures Formed by Spinodal Decomposition of Ferrite in Aged CF8 Cast Duplex Steel“. Microscopy and Microanalysis 6, S2 (August 2000): 362–63. http://dx.doi.org/10.1017/s1431927600034309.

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Phase separation by spinodal decomposition of body centered cubic Fe-Cr binary alloys to form isotropic fully interconnected nanostructures of Fe-rich α and Cr-enriched α′ phases typically on a scale of 2 to 10 nm is scientifically intriguing and technologically important. In aged dual-phase steels, it is the decomposition of the ferrite to form such α-α′ composition modulations that is primarily responsible for the increased ferrite hardness that contributes to embrittlement. The α′ structures are isotropic since the lattice constants of the two phases are almost identical and consequently the strain energy is small. In other spinodal systems larger strain energy leads to triaxially modulated structures aligned along <100> in cubic materials. A review of TEM characterization of spinodal alloys revealed that aligned structures had received the most attention, because they are more common and their characterization by TEM is more tractable.

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Negita, Keishi. „Electrorheological Effect in the Nematic and the Smectic A Phases of Low Molecular Weight Liquid Crystal“. International Journal of Modern Physics B 13, Nr. 14n16 (30.06.1999): 2005–10. http://dx.doi.org/10.1142/s0217979299002071.

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Electrorheological (ER) effects in the nematic (Ne), the smectic A (SmA) and the isotropic (Is) phases of octyloxy cyanobiphenyl (8OCB) are studied. When an electric field is applied, a large decrease of the viscosity is observed in the Sm A phase, while in the Ne phase an increase of the viscosity is recognized with an anomalous ER effect near the SmA-Ne phase transition. These behaviors are suggested to be general properties of the liquid crystal exhibiting the phase sequence of SmA-Ne-Is.

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Fernández-Rico, Carla, Massimiliano Chiappini, Taiki Yanagishima, Heidi de Sousa, Dirk G. A. L. Aarts, Marjolein Dijkstra und Roel P. A. Dullens. „Shaping colloidal bananas to reveal biaxial, splay-bend nematic, and smectic phases“. Science 369, Nr. 6506 (20.08.2020): 950–55. http://dx.doi.org/10.1126/science.abb4536.

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Understanding the impact of curvature on the self-assembly of elongated microscopic building blocks, such as molecules and proteins, is key to engineering functional materials with predesigned structure. We develop model “banana-shaped” colloidal particles with tunable dimensions and curvature, whose structure and dynamics are accessible at the particle level. By heating initially straight rods made of SU-8 photoresist, we induce a controllable shape deformation that causes the rods to buckle into banana-shaped particles. We elucidate the phase behavior of differently curved colloidal bananas using confocal microscopy. Although highly curved bananas only form isotropic phases, less curved bananas exhibit very rich phase behavior, including biaxial nematic phases, polar and antipolar smectic-like phases, and even the long-predicted, elusive splay-bend nematic phase.

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Sandmann, M., F. Hamann und A. Würflinger. „PVT and DTA Measurements on trans-4-n-Hexyl- (4'-Cyanophenyl)-Cyclohexane (6PCH) up to 300 MPa“. Zeitschrift für Naturforschung A 54, Nr. 5 (01.05.1999): 281–86. http://dx.doi.org/10.1515/zna-1999-0502.

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The phase diagram of trans-4-n-hexyl-(4'-cyanophenyl)-cyclohexane, (6PCH) has been established by high-pressure differential thermal analysis. Specific volumes are presented for temperatures between 300 and 370 K up to 300 MPa. The p,Vm ,T data have been determined for the nematic, isotropic, and (partly, in the neighbourhood to the melting curve) solid phases. Volume and enthalpy changes along the phase transitions have also been calculated. As previously, the p,Vm,T data were used to calculate the volume entropy for the nematic-isotropic transition. The molar volumes along the clearing line TNI (p) enabled us to calculate the molecular field parameter γ = ∂ln TNI/∂In VNI , being 4.1.

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