Polar Glass Research Articles

Elucidating the interaction between polar alkoxysilane-modified silicate glass and ionic surfactant in the obtainment of hydrophobic transparent film

Soda-lime-silicate glass is a widely used material in industry and everyday life. For some applications, it is important to have hydrophobic properties of its surface and at the same time retain the transparency in the visible spectrum. This can be achieved using fluoroalkyl silanes as surface modifiers. However, fluorine shows severe health effects and the nowadays tendency is to use more appropriate substances for surface modification. In this work, we show the possibility of obtaining a hydrophobic and transparent film on silicate glass using alkoxysilanes with alkyl groups possessing terminal -NH2 and subsequent modification of such silanized glass using an anionic surfactant. The possible mechanism of the interaction between the chemisorbed silyl group and the dodecyl sulfate ion was discussed.

Experimental examination of dipole-dipole cross-correlations by dielectric spectroscopy, depolarized dynamic light scattering, and computer simulations of molecular dynamics.

The contribution of cross- and self-correlations to the dielectric and light-scattering spectra of supercooled polar glass formers has recently become a most challenging problem. Herein, we employ dielectric spectroscopy, depolarized dynamic light scattering (DDLS), and rheology to thoroughly examine the dynamics of van der Waals liquid 1,2-Diphenylvinylene. Carbonate (DVC), which is a polar counterpart of canonical glass former ortho-Terphenyl (OTP). We show that the light-scattering data correspond well with the dielectric permittivity function over a wide T range. This pattern is very different from the peaks' separation ω_{max}^{DDLS}/ω_{max}^{BDS}=3.7 reported recently for tributyl phosphate (TBP), despite the same dielectric characteristics of these two glass formers (β_{KWW}=0.75,Δɛ=20 for both TBP and DVC; KWW stands for Kohlrausch-Williams-Watts). This indicates different influence of orientational correlations in both methods for these two systems. We also show the results of the computer simulations of the model, polar molecules, which clearly indicate that the contribution of the cross-term to the correlation function probed in the DDLS experiment can be significant.

A hybrid approach to oil structuring - combining wax oleogels and capillary suspensions.

There is continuing interest in finding new approaches to gel liquid oil for processed food applications. Here, we combined oleogels and capillary suspensions to generate model oil-continuous networks consisting of a wax oleogel and a water-bridged, glass particle network. The composition map tested comprised 30 vol% polar or non-polar glass beads dispersed in a 70 vol% non-particle phase consisting of water (≤9 vol%) as well as 2 wt% hexatriacontane as oleogelator in canola oil. While the hexatriacontane wax alone gelled the oil, presence of the glass beads (but no water) prevented oleogelation. Self-supporting capillary networks formed with polar particles and 1 vol% water or non-polar glass beads and 3 vol% water in canola oil. The capillary suspensions demonstrated significant differences in rheological behaviour as the polar particles yielded much higher elastic moduli than their non-polar particle counterparts. Polar hybrids were weakened by inclusion of the wax whereas the non-polar particle hybrid network displayed elastic moduli greater than the respective contributions of both capillary and wax gel networks. This hybrid method of oleogelation can be applied to virtually any food particles and uses minimal water and wax.

Non-simple flow behavior in a polar van der Waals liquid: Structural relaxation under scrutiny.

The non-exponential character of the structural relaxation is considered one of the hallmarks of the glassy dynamics, and in this context, the relatively narrow shape observed by dielectric techniques for polar glass formers has attracted the attention of the community for long time. This work addresses the phenomenology and role of specific non-covalent interactions in the structural relaxation of glass-forming liquids by the study of polar tributyl phosphate. We show that dipole interactions can couple to shear stress and modify the flow behavior, preventing the occurrence of the simple liquid behavior. We discuss our findings in the general framework of glassy dynamics and the role of intermolecular interactions.

An error compensation scheme for polar coordinate glass edging machines using the contour registration method

This paper proposes a comprehensive error compensation method for the glass edging machine using polar coordinates. An error model is established to evaluate the error source of the contour deviation from the ideal position after glass installation. According to the simulation results, it is determined that the misalignment of the linear axis and the rotary table and the inaccuracy of the fixture are the main reasons for the installation error of the work-piece. Then, a two-step contour registration method is introduced to accomplish the task of error identification. The glass contour is first measured by a laser displacement sensor after being installed on the rotary table. The coarse registration is presented to align the centroid positions of the measured and the ideal contours, and the fine registration is developed to match them precisely. After that, the installation error can be extracted from the transformation parameters by the least square method. Furthermore, a compensation model is proposed to map the original contour to the actual installation position using the transformation matrix constructed by the identified errors. Finally, a verification experiment is implemented that compares the grind edge without and with compensation to validate the efficiency and accuracy of the proposed method. After error compensation, the mean value and the variance value of the polar diameter deviation of the glass work-piece decreased by 87.5% and 83.0%, respectively. This paper provides a simple way to identify and compensate the installation errors online with high accuracy and efficiency. The proposed method can improve the machining accuracy of the polar coordinate glass edging machines and reduce glass waste.

Molecular Cross-correlations Govern Structural Rearrangements in a Nonassociating Polar Glass Former.

Self- and cross-correlation dynamics of deeply supercooled liquids were recently identified using photon correlation spectroscopy on the one hand and dielectric investigations on the other. These results fueled a controversial discussion whether the "generic" response identified by photon correlation spectroscopy, or rather the nonuniversal dielectric response, reflect the liquid's structural relaxation. The present study employs physical aging and oscillatory shear rheology to directly access the structural relaxation of a nonassociating glass-forming liquid and reveals that collective equilibrium fluctuations of simple liquids and not single-particle dynamics govern their structural relaxation. The present results thus challenge recent views that the glassy response of polar supercooled liquids can generically be decomposed into a Debye-type, supramolecular response and a single-particle dynamics with the latter reflecting the "true" structural relaxation. Furthermore, the current findings underscore the pivotal role dielectric spectroscopy plays in glass science as one of the rare molecular-level reorientation techniques that senses dynamical cooperativity directly.

346. Head to Toe Imaging of Complications and Sequelae of COVID- 19 and COVID-19 Vaccination

BackgroundCOVID 19 is associated with a hypercoagulable state with cytokine storm syndrome and thrombocytopenia leading to complications across various systems. COVID-19 infection, its treatment, resultant immunosuppression, and pre-existing comorbidities have made patients vulnerable to secondary infectionsMethodsWe systematically reviewed COVID-19 cases between Jan to May 2021 for pulmonary and extrapulmonary complications. Patients with recent COVID-19 vaccination and neurological symptoms were also included.Figure 1. “Black turbinate” sign of mucormycosis Contrast enhanced coronal T1 FS images of paranasal sinuses shows necrotic non-enhancing right superior and middle turbinates (*) with extension into the right orbital fat.FIGURE 2 - A composite image of Coronal CT of upper abdomen in arterial phase and lung bases in lung window showing wedge showing right renal infarcts (line arrow) due to inferior polar artery thrombosis and ground glass opacities (solid arrow) in lung bases. Results Neurological complications: Neurological complications include ischemic and haemorrhagic strokes. Other complications are encephalopathy, encephalitis, Guillain-Barré syndrome, acute hemorrhagic necrotizing encephalopathy. Demyelination and radiculopathies are seen as post vaccination complications. Mucormycosis: Unprecedented high rate of invasive fungal sinusitis in association with COVID -19 is reported from the Indian subcontinent. This has a propensity for intra orbital and intracranial extension. COVID -19 associated coagulopathy: COVID -19 is a pro-inflammatory hypercoagulable state. Pulmonary thromboembolism, deep venous thrombosis and catheter related thrombosis are well documented. Cardiac complications: Cardiac manifestations include Myocardial Injury with non-obstructed coronary arteries (MINOCA), myocarditis, myocardial ischemia, cardiomyopathy. Pulmonary complications and sequelae of COVID -19: Progression of lung injury to ARDS during the initial phase and fibrosis of parenchyma in the recovery phase. Spontaneous pneumomediastinum, pneumatoceles and pneumothorax and secondary infections are identified in our study. COVID- 19 associated gastrointestinal complications: Patients evaluated for renal colic, pancreatitis, cholecystitis showed, ground glass opacities or subpleural bands in typical Covid-19 distribution. COVID-19 may lead of acute kidney and bowel injury due to arterial thrombosis. COVID - 19 associated myonecrosis: Ischemia of the small caliber vessels may result in myonecrosis.FIGURE 3 - Coronal STIR image shows thickened and hyperintense trunks and divisions of the right brachial plexus suggestive of plexopathy in a COVID -19 patient with H/O recent COVID-19 vaccination. Figure 4. Axial CT chest section in lung window showing pneumothorax (white arrow) and pneumatocele ( grey arrow) with peripheral ground glass opacities and consolidations in both lungs. ConclusionAwareness of these unusual manifestations will facilitate an early diagnosis, improve management and help reduce morbidity and mortalityDisclosures All Authors: No reported disclosures

Two-Step Aging of Highly Polar Glass.

Nonequilibrium processes, including physical aging, belong to the most challenging phenomena of glassy dynamics. One of the fundamental problems that needs clarification is the effect of material polarity on the time scale of the structural recovery of glass. The importance of this issue arises from practical applications and recent findings suggesting a substantial contribution of dipole–dipole interactions to the dielectric permittivity spectra of polar glass-formers. Herein, we use dielectric spectroscopy to investigate structural relaxation and aging dynamics of highly polar glass-former 4-[(4,4,5,5,5-pentafluoropentoxy)methyl]-1,3-dioxolan-2-one (FPC), a derivative of propylene carbonate with εs = 180 and μ = 5.1. We show that ε″(tage) data of FPC at Tage < Tg reveal complex behavior resulting from considerable cross-correlation effects. Namely, two characteristic aging time scales, reflecting the evolution of cross-correlation mode and generic structural relaxation toward equilibrium, are obtained at a given Tage. Furthermore, a single stretched exponential behavior of ε″(tage) has been received for weakly polar carvedilol with negligible dipole–dipole interactions.

Reversible Adhesion Switching Using Spiropyran Photoisomerization in a High Glass Transition Temperature Polymer

Previous work has shown that photoisomerization of dopant molecules in a polystyrene film can either enhance or suppress its adhesion to a polar glass surface (Mostafavi, S. H. Macromolecules 2018, 51, 2388−2394; Mostafavi, S. H. Macromolecules 2019, 52, 6311–6317). In this paper, a different polymer host, Zeonex (ZX), is used in conjunction with the photochrome spiropyran. Nonpolar ZX has a higher glass transition temperature that makes it resistant to nanoscale mechanical deformations, while the spiropyran (SP) → merocyanine (MC) photoisomerization is a reversible reaction with a large polarity change. Ultraviolet light isomerizes SP to the polar MC form, increasing both the shear and pull-off adhesion forces to a clean glass surface by a factor of 5. Visible irradiation switches it back to the nonpolar SP form and returns the film back to its original weak adhesion, in contrast to the previously studied polystyrene films. The ability of visible light to switch off the polymer–glass adhesion is harnessed to make a light-controlled payload release device as well as to accelerate the polymer film delamination rate in water by a factor of 100. The kinetics of the water delamination, as well as the origin of residual adhesion after switching back to the SP form, are investigated. This work demonstrates how light-controlled noncovalent adhesion can be used as a solvent-free method to remove protective coatings or to disassemble structures.

Effect of Partial Ba Substitutions on the Crystallization of Sr2TiSi2O8 (STS) Glass-Ceramics and on the Generation of a SAW Signal at High Temperatures.

Because of their characteristics, including a d33 of 10–15 pC/N and high stability up to temperatures over 1000 °C, polar glass–ceramics containing fresnoite crystals can be regarded as highly effective materials for applications requiring piezoelectricity at high temperatures. In the present paper we investigate barium substitutions in an Sr-fresnoite (STS) glass–ceramic. Two aspects are studied: first, the effect of the substitution on the preferential orientation of the crystallization, and second, the ability of the glass–ceramics to generate and propagate surface acoustic waves (SAW) at high temperatures. XRD analyses show that a 10 at.% substitution of Ba allows us to keep a strong preferential orientation of the (00l) planes of the fresnoite crystals down to more than 1 mm below the surfaces. Higher substitution levels (25 and 50 at.%), induce a non-oriented volume crystallization mechanism that competes with the surface mechanism. SAW devices were fabricated from glass–ceramic substrates with 0, 10 and 25 at.% Ba substitutions. Temperature testing reveals the high stability of the frequency and delay for all of these devices. The glass–ceramic with a 10 at.% Ba substitution gives the strongest amplitude of the SAW signal. This is attributed to the high (00l) preferential orientation and the absence of disoriented volume crystallization.

SrTiO3—Glimpses of an Inexhaustible Source of Novel Solid State Phenomena

The purpose of this selective review is primarily to demonstrate the large versatility of the insulating quantum paraelectric perovskite SrTiO3 explained in “Introduction” part, and “Routes of SrTiO3 toward ferroelectricity and other collective states” part. Apart from ferroelectricity under various boundary conditions, it exhibits regular electronic and superconductivity via doping or external fields and is capable of displaying diverse coupled states. “Magnetoelectric multiglass (Sr,Mn)TiO3” part, deals with mesoscopic physics of the solid solution SrTiO3:Mn2+. It is at the origin of both polar and spin cluster glass forming and is altogether a novel multiferroic system. Independent transitions at different glass temperatures, power law dynamic criticality, divergent third-order susceptibilities, and higher order magneto-electric interactions are convincing fingerprints.

New Insights into the Role of the Surrounding Medium Temperature in the Under-Liquid Wetting of Solid Surfaces.

The wetting of a solid surface by a liquid droplet under a liquid medium at elevated temperatures depends not only on the solid-drop and drop-medium interfacial tensions (IFTs) but also on the temperature dependency of the IFT of the surrounding medium. Previous studies have shown either a decreasing or nearly invariant trend of wettability with an increase in temperature. However, much of the research up to now has only focused on the evaluation of solid wettability in air or vapor, and no model has been proposed to predict the variation of solid wettability at high temperatures under a liquid medium. Here, we developed a theoretical framework and a novel experimental approach to evaluate the high-temperature solid-liquid-liquid wettability. We investigated the wettability of different polymeric and nonpolymeric surfaces, namely, glass, silicon wafer, poly(methyl methacrylate) (PMMA), and polytetrafluoroethylene (PTFE), for a wide range of polar and nonpolar probe droplets under water (as a liquid medium) at temperatures up to 90 °C. The experimental results revealed that the nonpolymeric highly polar solid surfaces, that is, glass and silicon wafer, showed a sharp increase in their contact angle with the probe droplets at elevated temperatures. Between the two polymeric surfaces, PMMA showed a decreasing trend of the contact angle over the variation of temperatures, while in the case of PTFE, no specific trend was observed. The predictions of our theoretical model were in good agreement with the experimental observations with less than ±25% deviation.

Self-diffusion in ionic liquids with nitrate anion: Effects of confinement between glass plates and static magnetic field

Alkylammonium nitrate protic ionic liquids (ILs), when placed between flat polar borosilicate glass plates, have demonstrated enhanced diffusivity and the gradual decrease of diffusivity after exposure to an external static magnetic field (Filippov et al., 2018). This phenomenon has been explained by phase transformations taking place in the ILs. In this study, we observed similar processes occurring in systems prepared with ethylammonium nitrate confined between quartz plates. A higher content of silicon oxide in the plates does not significantly alter the phenomenon previously found in the system prepared with borosilicate glass plates. For the first time, we have observed similar effects of confinement and magnetic field on the aprotic IL, 1‑ethyl‑3‑methylimidazolium nitrate. Substitution of the ethylammonium cation with a 1‑ethyl‑3‑methylimidazolium cation slows down the kinetics and increases magnitude of the processes occurring in the IL exposed to a magnetic field. We suggested that the main factor determining these effects is the presence and modification of the hydrogen-bonding network in the studied protic and aprotic ILs. The process of inverse phase transformation for the confined ethylammonium nitrate after removing the sample from the magnetic field was observed and analysed.

Enhancement of Fracture Properties of Composite Laminate with Si C Additive

ASTM standards for short beam test, double cantilever beam and end notched specimen test are followed to compare control specimen with different percentage of Si C test data. Present study shows interlaminar shear strength (ILSS) and delamination fracture toughness values of multilayered composite laminate can be enhanced considerably with the use of Si C admixture in epoxy resin system as nonpolar elements compatible with to polar glass fiber. With respect to control specimen one percentage by weight of Si C w.r.t resin can bring up the ILSS value by as much 70% while the DCB test data on the critical energy release rate of mode I increases by 85% and mode II toughness value becomes double for 1% by weight of Si C. The bidirectional cloth provides more resistance for mode-I delamination fracture toughness when compared to UDL reported in literature and hence for higher fracture properties. The study is useful for design of rocket nozzles and input required for the cohesive zone model to assess the residual strength of composite structures with of delamination.

СИТАЛЛЫ ИЗ МЕСТНОГО СЫРЬЯ ДЛЯ ПРОИЗВОДСТВЕННЫХ ИННОВАЦИОННЫХ ИНФРАСТРУКТУР С ВЫСОКОЙ ТЕХНИКО-ЭКОНОМИЧЕСКОЙ ЭФФЕКТИВНОСТЬЮ В ЭКСТРЕМАЛЬНЫХ УСЛОВИЯХ КРАЙНЕГО СЕВЕРА

Актуальность исследования обусловлена проблемами эффективности освоения полезных ископаемых Заполярья за счет отказа от ввозимых за тысячи километров строительных материалов (бетонных изделий, кирпича и т. п.). Максимальная удаленность от промышленно-урбанизированных центров в сочетании с крайне суровыми природно-климатическими условиями Крайнего Севера значительно влияют на экономику добычи и экологию территории, где стоимость строительных материалов доходит до 70 % себестоимости нефти и газа. Выход на шельфы арктических морей России и других стран требует инновационных материалов и прорывных технологий, включая строительство искусственных островов и подводных сооружений на шельфе. Для реализации таких прорывных технологий необходимы материалы и конструкции, обладающие многократно большей прочностью и долговечностью. Цель исследования: разработать на основе сырья Полярного Урала многофункциональные материалы класса «сикам» с уникальным сочетанием физико-механических и химических свойств для передовых технологий. Объекты исследований: отвальные горные породы базитового ряда золоторудных месторождений Полярного Урала, метасиликатные расплавы, стекла и ситаллы. Методы исследований: теоретические и экспериментальные исследования исходных сырьевых материалов, расчет состава шихты для метасиликатных ситаллов – нового класса «сикам» (СКС), методы определения основных технологических параметров, изучения основных свойств продукции, методы создания новых инновационных строительных конструкций, методы обоснования технико-экономических показателей. Химический состав исходного сырья определен масс-спектральным методом с индуктивно связанной плазмой. Результаты исследований. Обоснованы исходные составы и установлены физико-химические свойства петроситаллов класса «сикам» из местного сырья золоторудных месторождений Полярного Урала. Показана экономическая эффективность и экологическая целесообразность производства материала на месте с использованием дешевого энергоносителя (попутного газа) в сравнении с ввозимым железобетоном. В особых условиях Арктики этот материал незаменим для производства свайно-эстакадной дорожной конструкции и строительства на ее основе долговечной транспортной инфраструктуры, промышленных и гражданских объектов в условиях вечной мерзлоты и арктического шельфа.

Self-diffusion of ethylammonium nitrate ionic liquid confined between modified polar glasses

Ethylammonium nitrate (EAN) ionic liquid confined between flat polar glass plates demonstrates variable diffusivity that is sensitive to an external static magnetic field. Outside the magnetic field, diffusivity between the plates is higher than that in the bulk. However, after placing the system in a strong static magnetic field, the diffusivity gradually decreased. These processes occur during transformations between phases formed in EAN subjected to micrometer-size restrictions outside and within the magnetic field (Filippov et al., J. Mol. Liq. [2018] 268, 49). In this study, we used samples of two types: (i) with roughened surface formed by treatment of the glass plates with aqueous solutions of hydrofluoric acid and (ii) with vacuum deposited TiO2 layers with a thickness of ca. 1 μm at glass-plate edges. Neither the surface modification of the glass plates, nor the TiO2 layers controlled thickness of EAN confined between glass-plates significantly changed the above-described effects, which have been observed in studies using untreated glass plates. Therefore, the range of systems with detected phase transformations in EAN and accompanying effects, such as accelerated diffusivity and change in diffusivity under the influence of a static magnetic field, was expanded to the systems with roughened surfaces and the systems with TiO2 layers controlled inter-plates distances. Results of experiments with roughened surfaces additionally suggested that the phase transformation of confined EAN in the external magnetic field is isotropic in nature rather than a phase transition from “layered to bulk” structures.

Rapid carbene formation increases ion diffusivity in an imidazolium acetate ionic liquid confined between polar glass plates.

1-Ethyl-3-methyl-imidazolium acetate ([EMIM][OAc]) is one of the most widely used ionic liquids for various applications. This study is focussed on the chemical stability of [EMIM][OAc] on the surfaces of polar glass plates. 1H and 13C NMR spectroscopy and NMR diffusometry of [EMIM][OAc] IL confined between glass plates with a specific surface area 105-106 m-1 are thoroughly investigated. A rapid and spontaneous reaction took place on the surfaces of glass plates leading to the formation of neutral chemical moieties as evident by the appearance of new signals in the 1H NMR spectra. These new products are assigned as N-heterocyclic carbene (NHC) and acetic acid. These neutral chemical moieties have significantly increased the ion diffusivity by dissociation of the cation and the anion in [EMIM][OAc] IL. The yield and rate of formation of NHC and acetic acid are found to increase with the increasing surface area of polar glass plates and the time of contact between the IL and glass surfaces. Based on NMR spectroscopy, a dissociative reaction mechanism is proposed for the formation of free NHC in the neat [EMIM][OAc] IL.

Effect of magnetic field on diffusion of ethylammonium nitrate – water mixtures confined between polar glass plates

We used 1H NMR diffusometry to study mixtures of ethylammonium nitrate (EAN) with water (3.1–12.4 mol% of added H2O) confined between polar glass plates and exposed to a static magnetic field of 9.4 T. The presence of such restrictions reverses the concentration dependence of the diffusivities of the EA (ethylammonium) cation and water typical for the bulk system. The presence of water weakens the effects of a static magnetic field on diffusion of the EA cation as well as on proton exchange of –NH3 groups. Surprisingly, the amplitude of the echo signal of water protons decreases during exposure to the magnetic field and finally disappears, a phenomenon that depends on the concentration of water in the system. Based on experimental data, we suggest that water in the system is present in two states with different dynamic properties. One type of water formed in confinement possesses NMR relaxation time typical for liquids; its diffusivity can be measured by 1H NMR. The second type of water is formed upon exposure of the sample of the first type to the magnetic field and eventually includes all the water in the system. This type of water possesses “solid-like” NMR relaxation features that makes it “invisible” to the NMR diffusometry technique. We suggest that this second type of water is adsorbed onto the glass plates. Correspondingly, EAN exists in two liquid phases: the first one contains an EAN-water mixture, while the second one contains neat EAN, and forms on the microscopic scale range under the influence of a static magnetic field.

Static magnetic field alters properties of confined alkylammonium nitrate ionic liquids

Ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) ionic liquids confined between polar glass plates and exposed to a strong magnetic field of 9.4 T demonstrate gradually slowing diffusivity, a process that can be reversed by removing the sample from the magnetic field. The process can be described well by the Avrami equation, which is typical for autocatalytic (particularly, nucleation controlled) processes. The transition can be stopped by freezing the sample. Cooling and heating investigations showed differences in the freezing and melting behavior of the sample depending on whether it had been exposed to the magnetic field. After exposure to the magnetic field, the sample demonstrated decrease in the 1H NMR signal of residual water. 1H NMR spectroscopy with presaturation demonstrates that the most probable mechanism of the decrease of the bulk water signal is adsorption of water on polar surfaces of glass plates. Generally, our findings confirm our previous suggestion that alteration of the dynamic properties of confined alkylammonium nitrate ionic liquids exposed to a magnetic field is related to the alteration of real physical-chemical phases.

Magnetic field effects dynamics of ethylammonium nitrate ionic liquid confined between glass plates.

Self-diffusion and NMR relaxation of the ethylammonium (EA) cation were studied in the protic ionic liquid, ethylammonium nitrate (EAN), confined between polar glass plates separated by a few μm distance and exposed to an external magnetic field of 9.4 T. The diffusion coefficient of EA (D) and the transverse NMR relaxation rate (1/T2) of -NH3 protons were increased immediately after placing the sample in the magnetic field by factors of ∼2 and ∼22, respectively, in comparison with those of bulk EAN. Further exposure of the sample to the magnetic field led to gradual changes in D, T1 and T2 towards their bulk values with a time constant of ∼70 min. Complete "recovery" of the sample to the "accelerated" D and "shortened" T2 values occurred at longer than 24 hours after the removal of the EAN sample from the magnet. Because the observed characteristic times of the change far exceed the times of molecular processes in EAN, we suggested that this phenomenon is related to reversible phase transformations occurring in confined EAN.