Showing papers on "Phase transition published in 1989"
TL;DR: It is argued that the superfluid-insulator transition in the presence of disorder may have an upper critical dimension dc which is infinite, but a perturbative renormalization-group calculation wherein the critical exponents have mean-field values for weak disorder above d=4 is also discussed.
Abstract: The phase diagrams and phase transitions of bosons with short-ranged repulsive interactions moving in periodic and/or random external potentials at zero temperature are investigated with emphasis on the superfluid-insulator transition induced by varying a parameter such as the density. Bosons in periodic potentials (e.g., on a lattice) at T=0 exhibit two types of phases: a superfluid phase and Mott insulating phases characterized by integer (or commensurate) boson densities, by the existence of a gap for particle-hole excitations, and by zero compressibility. Generically, the superfluid onset transition in d dimensions from a Mott insulator to superfluidity is ‘‘ideal,’’ or mean field in character, but at special multicritical points with particle-hole symmetry it is in the universality class of the (d+1)-dimensional XY model. In the presence of disorder, a third, ‘‘Bose glass’’ phase exists. This phase is insulating because of the localization effects of the randomness and analogous to the Fermi glass phase of interacting fermions in a strongly disordered potential. The Bose glass phase is characterized by a finite compressibility, no gap, but an infinite superfluid susceptibility. In the presence of disorder the transition to superfluidity is argued to occur only from the Bose glass phase, and never directly from the Mott insulator. This zero-temperature superfluid-insulator transition is studied via generalizations of the Josephson scaling relation for the superfluid density at the ordinary λ transition, highlighting the crucial role of quantum fluctuations. The transition is found to have a dynamic critical exponent z exactly equal to d and correlation length and order-parameter correlation exponents ν and η which satisfy the bounds ν≥2/d and η≤2-d, respectively. It is argued that the superfluid-insulator transition in the presence of disorder may have an upper critical dimension dc which is infinite, but a perturbative renormalization-group calculation wherein the critical exponents have mean-field values for weak disorder above d=4 is also discussed. Many of these conclusions are verified by explicit calculations on a model of one-dimensional bosons in the presence of both random and periodic potentials. The general results are applied to experiments on 4He absorbed in porous media such as Vycor. Some measurable properties of the superfluid onset are predicted exactly [e.g., the exponent x relating the λ transition temperature to the zero-temperature superfluid density is found to be d/2(d-1)], while stringent bounds are placed on others. Analysis of preliminary data is consistent with these predictions.
2,472 citations
TL;DR: In this article, the ferroelectric properties of copolymers of vinylidene fluoride with trifluoroethylene and tetrafluorethylene are described with special interest in their polarization reversal and phase transition behavior.
Abstract: Ferroelectric properties of copolymers of vinylidene fluoride with trifluoroethylene and tetrafluoroethylene are described with special interest in their polarization reversal and phase transition behavior. The ferroelectric phase consists of all-trans molecules packed in a parallel fashion while molecules adopt irregular TT, TG, T[Gbar] conformations in the paraelectric phase. In the ferroelectric phase, polarization reversal occurs at very high fields (> 100 MV/m) as a result of eventual 180° rotations of individual chain molecules around their axes. The switching time ranges from sec to nsec depending upon the strength of the applied field according to an exponential law with a particularly large activation field (∼ 1 GV/m). The value of the observed remnant polarization is consistent with prediction from a simple dipole sum implying a minor contribution from the Coulomb interaction. The ferroelectric-to-paraelectric transition appears most clearly for copolymers containing 50-80 mol% vinylide...
977 citations
01 Nov 1989
607 citations
TL;DR: For random-field models, this work rigorously proves uniqueness of the Gibbs state 2D Ising systems, and absence of continuous symmetry breaking in the Heisenberg model in d\ensuremath{\le}4, as predicted by Imry and Ma.
Abstract: It is shown, by a general argument, that in 2D quenched randomness results in the elimination of discontinuities in the density of the thermodynamic variable conjugate to the fluctuating parameter. Analogous results for continuous symmetry breaking extend to d\ensuremath{\le}4. In particular, for random-field models we rigorously prove uniqueness of the Gibbs state 2D Ising systems, and absence of continuous symmetry breaking in the Heisenberg model in d\ensuremath{\le}4, as predicted by Imry and Ma. Another manifestation of the general statement is found in 2D random-bond Potts models where a phase transition persists, but ceases to be first order.
453 citations
TL;DR: In this article, a summary of recent mathematical advances in the theory of defects in nematic liquid crystals is presented, including some new results concerning disclinations (line defects) which have not been published elsewhere.
Abstract: This is a summary of some recent mathematical advances in the theory of defects in nematic liquid crystals. It also includes some new results concerning disclinations (line defects) which have not been published elsewhere.
425 citations
TL;DR: In this paper, the authors developed a thermodynamic phenomenological theory to model the phase transitions and single-domain properties of the lead zirconate-titanate (PZT) solid solution system.
Abstract: Compositions within the lead zirconate-titanate (PZT) solid solution system have been extensively used in polycrystalline ceramic form in a wide range of piezoelectric transducer applications. However, the growth of good quality PZT single crystals for compositions across the entire phase diagram has not been accomplished. Due to the lack of single-crystal data, an understanding of the properties of polycrystalline PZT has been limited. If the single domain (intrinsic) properties of PZT could be determined, then the extrinsic contributions (e.g. domain wall and defect motions) to the polycrystalline properties could be separated from the intrinsic contributions. The purpose of this research has been to develop a thermodynamic phenomenological theory to model the phase transitions and single-domain properties of the PZT system. This paper is the first of a series of five papers describing the thermodynamic theory of PZT that has been developed for the entire solid solution system. In this paper th...
392 citations
TL;DR: Theorie phenomenologique de la dynamique de fluctuations de concentration de solutions de polymere en ecoulement cisaille simple isabelle simple est disponible.
Abstract: We present a phenomenological theory for the dynamics of concentration fluctuations of polymer solutions in the presence of simple shear flow. A coupling between concentration fluctuations and stress exists in the system as a result of the concentration dependence of viscosity and normal stress coefficients. Linear analysis indicates that scattering is greatly enhanced by the flow, even at temperatures significantly above the equilibrium coexistence curve. This may explain experimental observations of turbidity above the equilibrium transition, but this would not be a true shift in the phase transition.
313 citations
TL;DR: A correlation between liposome fusion kinetics and lipid phase behavior for several inverted phase forming lipids is found and it is likely that membrane fusion and the L alpha/inverted cubic phase transition proceed via a common set of intermembrane intermediates.
Abstract: We have found a correlation between liposome fusion kinetics and lipid phase behavior for several inverted phase forming lipids. N-Methylated dioleoylphosphatidylethanolamine (DOPE-Me), or mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), will form an inverted hexagonal phase (HII) at high temperatures (above TH), a lamellar phase (L alpha) at low temperatures, and an isotropic/inverted cubic phase at intermediate temperatures, which is defined by the appearance of narrow isotropic 31P NMR resonances. The phase behavior has been verified by using high-sensitivity DSC, 31P NMR, freeze-fracture electron microscopy, and X-ray diffraction. The temperature range over which the narrow isotropic resonances occur is defined as delta TI, and the range ends at TH. Extruded liposomes (approximately 0.2 microns in diameter) composed of these lipids show fusion and leakage kinetics which are strongly correlated with the temperatures of these phase transitions. At temperatures below delta TI, where the lipid phase is L alpha, there is little or no fusion, i.e., mixing of aqueous contents, or leakage. However, as the temperature reaches delta TI, there is a rapid increase in both fusion and leakage rates. At temperatures above TH, the liposomes show aggregation-dependent lysis, as the rapid formation of HII phase precursors disrupts the membranes. We show that the correspondence between the fusion and leakage kinetics and the observed phase behavior is easily rationalized in terms of a recent kinetic theory of L alpha/inverted phase transitions. In particular, it is likely that membrane fusion and the L alpha/inverted cubic phase transition proceed via a common set of intermembrane intermediates.
303 citations
15 Mar 1989
TL;DR: In this article, the authors present a study of the order-disorder and BCC-FCC transitions of a model colloidal suspension of highly charged polystyrene spheres as a function of particle volume fraction and the ionic strength.
Abstract: We present a study of the order-disorder and BCC-FCC transitions of a model colloidal suspension of highly charged polystyrene spheres as a function of the particle volume fraction and the ionic strength. We analyze Kossel lines, produced by backscattered light diffraction, to identify the crystal structures and determine the interparticle spacings. Our results consist of phase diagrams showing that the BCC structure is stable at ionic strengths lower than 2.7 × 10−6 M KCl and volume fractions less than 0.008. We compare our experimentally determined phase diagrams with recent analytical models and with the molecular dynamics (MD) simulations of Kremer, Robbins, and Grest. The effective hard sphere prediction of the order-disorder boundary overestimates the phase transition at low ionic strengths and underestimates it at high ionic strengths for both the constant-charge and constant-potential approximations. Analytical models predicting the BCC-FCC transition boundary from either the internal energy or the free energy difference between the two states are in clear disagreement with both the MD results and our data. Using a renormalized charge, we find very good agreement between our experimental results and the MD predictions for both the solid-liquid and solid-solid transitions.
288 citations
TL;DR: In this article, the authors investigated the effect of field-induced phase change between the antiferroelectric and ferroelectric states in tetragonal (Pb0.97 La 0.02 )(Sn,Ti, Zr)O3 ceramics for high-strain displacement transducer applications.
Abstract: Several properties associated with the field‐induced phase change between the antiferroelectric and ferroelectric states in tetragonal (Pb0.97 La0.02 )(Sn,Ti,Zr)O3 antiferroelectric ceramic family were investigated for high‐strain displacement transducer applications. The longitudinal field‐induced strain accompanying the phase change is in the range of 0.2%–0.9%. The single‐shot switching time between the two states is on the order of 1–2 μs. Under continuous ac field driving, the hysteretic heating effect introduces a temperature rise, changing the original room‐temperature switching behavior. The ceramics degrade under ac field excitation, the average life cycles is in the range of 106 –107 cycles which can be greatly improved by carefully polishing the sample surfaces.
283 citations
TL;DR: Investigation of disruption of tight packing of side chains in protein core shows that this disruption is an “all‐or‐none” transition (independent of how compact is the denatured state of a protein and independent of the protein–solvent interactions) because expansion of a globule must exceed some threshold to release rotational isomerization of side Chains.
Abstract: A theory of equilibrium denaturation of proteins is suggested. According to this theory, a cornerstone of protein denaturation is disruption of tight packing of side chains in protein core. Investigation of this disruption is the object of this paper. It is shown that this disruption is an "all-or-none" transition (independent of how compact is the denatured state of a protein and independent of the protein-solvent interactions) because expansion of a globule must exceed some threshold to release rotational isomerization of side chains. Smaller expansion cannot produce entropy compensation of nonbonded energy loss; this is the origin of a free-energy barrier (transition state) between the native and denatured states. The density of the transition state is so high that the solvent cannot penetrate into protein in this state. The results obtained in this paper make it possible to present in the following paper a general phase diagram of protein molecule in solution.
TL;DR: In this article, electric-field-forced antiferroelectric-to-ferroelectric phase transitions in several compositions of modified lead zirconate titanate stannate (Zr0.66Ti0.09Sn0.25)O3 ceramics are studied for ultra-high-fieldinduced strain actuator applications.
Abstract: Electric-field-forced antiferroelectric-to-ferroelectric phase transitions in several compositions of modified lead zirconate titanate stannate antiferroelectric ceramics are studied for ultra-high-field-induced strain actuator applications. A maximum field-induced longitudinal strain of 0.85% and volume expansion of 0.95% are observed in the ceramic composition Pb0.97La0.02(Zr0.66Ti0.09Sn0.25)O3 at room temperature. Switching from the antiferroelectric form to the ferroelectric form is controlled by the nucleation of the ferroelectric phase from the antiferroelectric phase. A switching time of <1 μs is observed under the applied field above 30 kV/cm. The polarization and strains associated with the field-forced phase transition decrease with increasing switching cycle, a so-called fatigue effect. Two types of fatigue effects are observed in these ceramic compositions. In one, the fatigue effects only proceed to a limited extent and the properties may be restored by annealing above the Curie temperature, while in the other, the fatigue effects proceed to a large extent and the properties cannot be restored completely by heat treatment. Hydrostatic pressure increases the transition field and the switching time. But when the applied electric field is larger than the transition field, the induced polarization and strain are not sensitive to increasing hydrostatic pressure until the transition field approaches the applied field.
TL;DR: In this article, it was argued that bond randomness drastically alters multicritical phase diagrams via a random-field mechanism, and the phase transitions of q-state Potts models are second order for all q at dimensionality d\ensuremath{\le}2.
Abstract: It is argued on general grounds that bond randomness drastically alters multicritical phase diagrams via a random-field mechanism. For example, tricritical points and critical end points are entirely eliminated (d\ensuremath{\le}2) or depressed in temperature (dg2). These predictions are confirmed by a renormalization-group calculation. Another consequence of this phenomenon is that, under bond randomness, the phase transitions of q-state Potts models are second order for all q at dimensionality d\ensuremath{\le}2.
TL;DR: In this paper, the same underlying physics which controls both growth processes is discussed, which leads to morphological instability in which a growing surface is unstable with respect to spacially periodic perturbations.
Abstract: What does viscous fingering have in common with crystal growth? It is not only the visual similarity of the patterns the two seemingly unrelated phenomena can generate under certain circumstances, but also the same underlying physics which controls both growth processes. The common behaviour - diffusion limited growth - leads to morphological instability in which a growing surface is unstable with respect to spacially periodic perturbations. Several theoretical and simulation studies have shown that the simple model is biased in its large scale morphology by the local anisotropy of the growth rules. Liquid crystals exhibit inherent anisotropies tunable with temperature in their bulk properties, which makes them extremely attractive for experimental studies of pattern forming processes. Electrohydrodynamic instabilities, transient patterns at the Frederiksz transition, directional solidification at an isotropic-nematic and cholesteric-smectic A phase transition, viscous fingering and dendritic "smectification" are discussed.
TL;DR: In this article, it was shown that 5-G magnetic fields could form on scales of 1 m when the temperature of the universe was around 150 MeV, and these primordial fields, a consequence of the QCD phase transition, have a magnitude of about 2 x 10 to the -17th G at the time when galaxy formation begins.
Abstract: If the QCD phase transition is first-order, then a thermoelectric mechanism generates magnetic fields in the early universe. For reasonable transition parameters, it is found that 5-G magnetic fields could form on scales of 1 m when the temperature of the universe was around 150 MeV. These primordial fields, a consequence of the QCD phase transition, have a magnitude of about 2 x 10 to the -17th G at the time when galaxy formation begins. 43 refs.
TL;DR: In this article, a simple graphical approach using free energy-composition diagrams and loci of thermodynamic instability delineating regions of continuous transformation is used to develop a framework for understanding the interplay between clustering and ordering occurring in metallic solid solutions where the ordered precipitate stems from a phase diagram configuration in which the ordered and disordered states are connected by a first-order phase transition.
TL;DR: acoustic velocity data are presented that demonstrate high-pressure solid-solid phase transition in molybdenum at about 2.1 Mbar and 4100 K, supported here by first-principles theoretical calculations which predict a zero-temperature bcc..-->..hcp transition within the experimental pressure range.
Abstract: We present acoustic velocity data that demonstrate a high-pressure solid-solid phase transition in molybdenum at about 2.1 Mbar and 4100 K. This observation is supported here by first-principles theoretical calculations which predict a zero-temperature bcc\ensuremath{\rightarrow} hcp transition within our experimental pressure range. In addition, our results show the melting transition for shock-compressed Mo at about 3.9 Mbar and 10000 K.
TL;DR: In this article, the Gibbs-Thompson relation for surface tension was proved in the context of the phase field model of free boundaries arising from phase transitions, and the main result is that λ is asymptotically equal to λ/d+o(λ), with E the interfacial energy, per unit surface area, of the interface between phases, and d the density jump across the interface.
Abstract: This paper discusses the asymptotic behavior as ɛ → 0+ of the chemical potentials λɛ associated with solutions of variational problems within the Van der Waals-Cahn-Hilliard theory of phase transitions in a fluid with free energy, per unit volume, given by ɛ2¦▽ϱ¦2+ W(ϱ), where ϱ is the density. The main result is that λɛ is asymptotically equal to ɛEλ/d+o(ɛ), with E the interfacial energy, per unit surface area, of the interface between phases, λ the (constant) sum of principal curvatures of the interface, and d the density jump across the interface. This result is in agreement with a formula conjectured by M. Gurtin and corresponds to the Gibbs-Thompson relation for surface tension, proved by G. Caginalp within the context of the phase field model of free boundaries arising from phase transitions.
TL;DR: In this article, the second harmonic generation of light, high resolution X-ray diffraction, quasi-elastic neutron scattering, small angle x-ray scattering, Brillouin scattering, far infrared absorption and submillimeter dielectric spectroscopy were used to investigate the ferroelectric phase and phase transition of VDF-TrFE copolymers.
Abstract: P(VDF-TrFE) copolymers with approximately 30 mol% of TrFE content exhibit above room temperature a ferroelectric transition of first order type with a large thermal hysteresis. We present recent investigations of the ferroelectric phase and of the phase transition using several techniques: second harmonic generation of light, high resolution X-ray diffraction, quasi-elastic neutron scattering, small angle X-ray scattering, Brillouin scattering, far infrared absorption and submillimeter dielectric spectroscopy. These results provide information on both the small crystallites and the amorphous inter-crystalline regions and show that temperature cycling throughout the Curie transition is able to modify the superstructure and to enhance the degree of crystallinity of the polymer. Accordingly, low frequency dielectric measurements, thermal expansion results and Brillouin spectroscopic investigations can be discussed in taking into account the composite structure of the semi-crystalline material.
TL;DR: In this article, high-pressure optical and spectroscopic techniques were used to obtain directly the ice I(h) - hda-ice transformation in a diamond-anvil cell, and the stability of the amorphous form is examined as functions of pressure and temperature.
Abstract: High-pressure optical and spectroscopic techniques were used to obtain directly the ice I(h) - hda-ice transformation in a diamond-anvil cell, and the stability of the amorphous form is examined as functions of pressure and temperature. It is demonstrated that hda-ice transforms abruptly at 4 GPa and 77 K to a crystalline phase close in structure to orientationally disordered ice-VII and to a more highly ordered, ice-VIII-like structure at higher temperatures. This is the first time that an amorphous solid is observed to convert to a crystalline solid at low temperatures by compression alone. Phase transitions of this type may be relevant on icy planetary satellites, and there may also be implications for the high-pressure behavior of silica.
TL;DR: In this article, the stability and P-V equation of state of CaSiO3 have been investigated using in situ diamond-anvil X ray diffraction techniques to 134 GPa, a pressure equivalent to that at the core-mantle boundary.
Abstract: The stability and P-V equation of state of CaSiO3 have been investigated using in situ diamond-anvil X ray diffraction techniques to 134 GPa, a pressure equivalent to that at the core-mantle boundary. Samples were heated by YAG laser at each pressure increment at high pressures to accelerate phase transitions. X ray diffraction measurements were carried out at 300 K using both energy-dispersive synchrotron and sealed-tube film techniques. Quenched CaSiO3-perovskite was observed to remain metastable close to 0.1 MPa, and to convert rapidly to an amorphous phase on pressure release. The simple cubic perovskite phase of CaSiO3 was found to be the stable phase for all lower mantle pressure conditions. All 47 P-V data points were used to obtain a third-order Birch-Murnaghan equation of state with zero-pressure parameters: unit cell volume V0 = 45.37±(0.08) A3, density ρ0 = 4.252(±0.008) Mg/m3, and bulk modulus K0 = 281(±4) GPa, with an assumed bulk modulus pressure K0′ = 4. These parameters are close to those of (Mg0.88Fe0.12)SiO3-perovskite and to those inferred by the Preliminary Reference Earth Model for the lower mantle. Hence, CaSiO3 must be considered an invisible component, in terms of density and bulk modulus constraints, in the lower mantle. Mantle composition models with both high and low calcium content can satisfy existing seismological constraints for the lower mantle.
TL;DR: In this article, the role of optic and acoustic phonons in the phase transition of ferroelectric fluorine polymers has been discussed based on the temperature dependences of the far-infrared spectra and the ultrasonic velocity.
Abstract: The structural phase transition has been investigated by X-ray diffraction and infrared and Raman spectroscopic measurements for ferroelectric fluorine polymers, including poly(vinylidene fluoride) and its copolymers with trifluoroethylene or tetrafluoroethylene. One of the most characteristic features of this ferroelectric transition is the large conformational change of the molecular chains between the trans and gauche rotational isomers, quite different from the structural change observed generally in the usual ionic ferroelectric materials. The crystallization and transition behaviors depend sensitively on the monomer composition in the copolymers as well as on the sample preparation conditions. The roles of the optic and acoustic phonons in the ferroelectric phase transition have been discussed based on the temperature dependences of the far-infrared spectra and the ultrasonic velocity.
TL;DR: In this article, the phase transitions from amorphous to crystalline states by applying electrical pulses were studied for sandwich structures of metal/GexTe100-x thin film/metal.
Abstract: The phase transitions from amorphous to crystalline states, and vice versa, by applying electrical pulses were studied for sandwich structures of metal/GexTe100-x thin film/metal. A systematic study of the crystallization temperature in GexT100-x(5\leqslant x \leqslant 30) thin films has been carried out. In some compositions, more than 104 repetitions of amorphous to crystalline states, and vice versa, were attained by the application of electric pulses. A model is proposed to explain the results observed.
TL;DR: Sharply faceted σ3 asymmetric tilt boundaries in Al and Au were prepared at room temperature and were then observed continuously by hot stage electron microscopy as they were heated to elevated temperatures and then cooled back to room temperature.
TL;DR: In this article, the high temperature phase transitions and conductitivity of dihydrogen phosphates and arsenates were investigated in terms of the proton transport model, taking into consideration the migration of protons between normal and interstitial proton sites.
Abstract: The high temperature phase transitions and conductitivity have been studied in some single crystals of the alkaly dihydrogen phosphates and dihydrogen arsenates. The quite different nature of the high temperature phase transitions in KDP and RDP in contrast with those in CDP and CDA is established. It is shown that the high temperature cubic phases in CDP and CDA are superionic ones. The experimental results are analyzed in terms of proton transport model, taking into consideration the migration of protons between normal and interstitial proton sites.
TL;DR: In this paper, the influence of external mechanical stress on the nematic-isotropic phase transformation of elastomers was investigated, and the experimental results of IR-dichroism measurements in the iridium phase and stress-optical measurements in isotropic phase were in good agreement with the theoretical predicitions of the phenomenological Landau-de Gennes theory.
Abstract: The influence of external mechanical stress on the nematic-isotropic phase transformation of nematic elastomers was investigated. The experimental results of IR-dichroism measurements in the nematic phase and stress-optical measurements in the isotropic phase are in good agreement with the theoretical predicitions of the phenomenological Landau-de Gennes theory. This is for the first time that a significant influence of an external field on the nematic-isotropic phase transformation temperature and on the nematic order parameter S has been proved.
TL;DR: A novel transition between distinct fractional quantum Hall states sharing the same filling fraction ν=8/5 is observed, implying a transition from a spin-unpolarized quantum fluid at small angles to a polarized one at higher angles.
Abstract: We observe a novel transition between distinct fractional quantum Hall states sharing the same filling fraction ν=8/5. The transition is driven by tilting the two-dimensional electron-gas sample relative to the external magnetic field and is manifested by a sharp change in the dependence of the measured activation energy on tilt angle. After an initial decline, the activation energy abruptly begins to increase as the tilt angle exceeds about 30°. A plausible model for these results implies a transition from a spin-unpolarized quantum fluid at small angles to a polarized one at higher angles.
TL;DR: In this article, a theory is presented to describe the nucleation and subsequent growth of weakly inhomogeneous lamellar phases from a supercooled disordered phase, and the authors find unusually small nucleation barriers and critically slowed growth kinetics.
Abstract: A theory is presented to describe the nucleation and subsequent growth of weakly inhomogeneous lamellar phases from a supercooled disordered phase. Detailed calculations are performed for the case of near‐symmetric diblock copolymer melts, although the results have relevance for other physical systems in the Brazovskii ‘‘universality class.’’ Nucleation phenomena in such systems are particularly interesting because the bulk phase transitions have a very weak, fluctuation‐induced first order character. We find unusually small nucleation barriers and critically slowed growth kinetics. For a diblock copolymer melt with degree of polymerization N and undercooling δ∝(Tt−T)/Tt≪1, the barrier is of order ΔF*/kBT∼N−1/3δ−2. Our estimate for the completion time of the nucleation and growth processes is θc ∼N1/12 δ−3/4 τd exp(ΔF*/4kBT), where τd is the copolymer terminal relaxation time.
TL;DR: Spin configurations of fractions zl\ensuremath{
u}l2 are examined by angular and n-dependent activation studies to quantify a dramatic difference between (4/3 and (5/3) states consistent with assignments.
Abstract: Spin configurations of fractions zl\ensuremath{
u}l2 are examined by angular and n-dependent activation studies. Energy gaps \ensuremath{\Delta}(\ensuremath{\theta}) and intercepts ${\ensuremath{\sigma}}_{\mathrm{xx}}^{c}$(\ensuremath{\theta}) that probe the quasiparticle charge ${e}^{\mathrm{*}}$ quantify a dramatic difference between (4/3 and (5/3 states consistent with assignments (4/3\ensuremath{\uparrow}\ensuremath{\downarrow}, and (5/3\ensuremath{\uparrow}\ensuremath{\uparrow} (\ensuremath{\uparrow}\ensuremath{\downarrow},\ensuremath{\uparrow}\ensuremath{\uparrow}=zero, maximum polarization). A field-induced phase transition $_{3}^{4}\ensuremath{\rightarrow}_{3}^{4}$ (partial polarization) in which ${e}^{\mathrm{*}}$ changes from e/3 to e/5 is mapped out. The (7/5 state formed from e/3 quasiparticles is destroyed at the (4/3 transition. High-order assignments $_{5}^{7}$(\ensuremath{\uparrow}\ensuremath{\uparrow} or \ensuremath{\downarrow}), $_{5}^{8}$ \ensuremath{\uparrow}\ensuremath{\downarrow}, $_{7}^{10}$ \ensuremath{\uparrow}\ensuremath{\downarrow}, and $_{7}^{11}\mathrm{\ensuremath{\uparrow}}$ are consistent with experiment.
TL;DR: Evidence from which it is suggested that this permeability change is due to a gel to liquid-crystaline phase transition accompanying rehydration is presented and it is shown that these principles can be extended to intact cells.
Abstract: Dry phospholipid bilayers are known to undergo transient changes in permeability during rehydration. In this review, we present evidence from which we suggest that this permeability change is due to a gel to liquid-crystalline phase transition accompanying rehydration. If the transition is avoided, as in lipids that remain in gel phase whether dry or rehydrated, the problem of leakage during rehydration is obviated, at least in part. Further, the evidence that the transition temperature for dry bilayers can be depressed by certain sugars is discussed. Finally, we show that these principles can be extended to intact cells. Using pollen grains as a model, we have measured the transition temperature for membrane phospholipids and show that the transition is correlated with physiological measurements including permeability changes and subsequent germination. From the Tm values taken from pollen grains at different water contents, we have constructed a phase diagram for the intact pollen that has high predictive value for physiological properties.