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Thanks to their prominent collective character, long-range interactions promote information spreading and generate forms of entanglement scaling, which cannot be observed in traditional systems with local interactions. In this work, we study the asymptotic behavior of the entanglement entropy for Kitaev chains with long-range hopping and pairing couplings decaying with a power law of the distance. We provide a fully-fledged analytical and numerical characterization of the asymptotic growth of the ground state entanglement in the large subsystem size limit, finding that the truly non-local nature of the model leads to an extremely rich phenomenology. Most significantly, in the strong long-range regime, we discovered that the system ground state may have a logarithmic, fractal, or volume-law entanglement scaling, depending on the value of the chemical potential and on the strength of the power law decay., Journal of High Energy Physics, 2023 (5), ISSN:1126-6708, ISSN:1029-8479

Summary The effects of reaction kinetics of bridgmanite and ferropericlase transforming to ringwoodite on elastic properties in upwelling mantle are investigated using data of kinetic experiments and internally self-consistent thermodynamic modelling of density and seismic velocities. The kinetic experiments show inhibited grain growth of ringwoodite. At the initiation of ringwoodite growth, bridgmanite completely transforms to a metastable pyrope-bearing garnet. Ringwoodite then gradually grows from the metastable assemblage of ferropericlase and garnet. The changes in mineralogy result in a low-velocity zone directly above the 660 km seismic discontinuity due to the lower seismic velocities and densities of ferropericlase and garnet compared to ringwoodite and bridgmanite. The modelling of the effects of reaction kinetics and its effect on seismic structure at ∼660 km depth shows more sensitivity to grain size than to temperature and upwelling rate. Modelling 1-D synthetic seismograms of PP (SS) underside reflections off the kinetically inhibited backward reaction to ringwoodite shows advanced traveltimes of underside reflections off ∼660 km depth of 0.2–0.8 s (1.2–1.6 s) for upwelling rates of 50 cm yr–1 and initial grain sizes between 5 and 20 cm due to the low-velocity zone above the 660 km discontinuity. The finite width of the low-velocity layer results in frequency-dependent behaviour of PP and SS underside reflection amplitudes, with higher amplitudes towards shorter periods. The effect on the traveltimes of P-to-s conversions used for receiver function is small (

International audience; We report bulk dilatometry and diffraction data through the T MIT = 427 K metal-insulator transition of the n = 3 member of the V n O 2n-1 Magnéli series. Besides VO 2 , V 3 O 5 is the only other vanadium oxide with a potentially useful MIT transition above room temperature. A narrow (ΔT = 10 K) abrupt negative thermal expansion of α L =-21.4 x 10-6 (dilatometry) and α V =-213 x 10-6 K-1 (crystallographic) is observed. We argue that the combination of the MIT along with the simultaneous vanadium charge ordering are responsible for such large values. The low temperature magnetic properties are also clarified and neutron diffraction measurements show a k = [½ ½ 0] magnetic structure at 1.5 K. DFT calculations of the exchange interactions support the low dimensionality and allow modelling the magnetic susceptibility.

In this work, we used Raman spectroscopic and optical absorption measurements and first-principles calculations to unravel the properties of wolframite-type ScNbO4 at ambient pressure and under high pressure. We found that monoclinic wolframite-type ScNbO4 is less compressible than most wolframites and that under high pressure it undergoes two phase transitions at ∼5 and ∼11 GPa, respectively. The first transition induces a 9% collapse of volume and a 1.5 eV decrease of the band gap energy, changing the direct band gap to an indirect one. According to calculations, pressure induces symmetry changes (P2/c–Pnna–P2/c). The structural sequence is validated by the agreement between phonon calculations and Raman experiments and between band structure calculations and optical absorption experiments. We also obtained the pressure dependence of Raman modes and proposed a mode assignment based upon calculations. They also provided information on infrared modes and elastic constants. Finally, noncovalent and charge analyses were employed to analyze the bonding evolution of ScNbO4 under pressure. They show that the bonding nature of ScNbO4 does not change significantly under pressure. In particular, the ionicity of the wolframite phase is 61% and changes to 63.5% at the phase transition taking place at ∼5 GPa.

Molecular switches are molecules that reversibly transform between two or more states inresponse to external stimuli such as light, heat, electric current, and pH. These molecules havebeen studied for a wide range of applications such as drug delivery, sensing, energy storage, andnanotechnology due to the significant changes in physical and optical properties upon switching.In this thesis, I have studied the fundamental behavior of a diverse set of molecular switches thatcan switch using light (photoswitches) in the solid state. Because the isomerization ofconventional photoswitches is typically studied in dilute solution or condensed liquid phases,there is an interest in investigating solid-state isomerization, especially for energy storageapplications. By studying solid-state energy storage materials, there is hope to increase theenergy harvesting density while avoiding the potential risk of organic liquid leakage andcombustion. In my thesis, I will cover crystal-to-amorphous photoswitchable phase changematerials as well as crystal-to-crystal photoswitchable phase change materials for energy storage through different types of systems. This thesis will hopefully provide insight helpful fordesigning solid-state molecular photoswitches and their application for energy storage.

In this article, starting from a Gibbs capacity, we build a new random capacity by applying two simple operators, the first one introducing some redundancy and the second one performing a random sampling. Depending on the values of the two parameters ruling the redundancy and the sampling, the new capacity has very different multifractal behaviors. In particular, the multifractal spectrum of the capacity may contain two to four phase transitions, and the multifractal formalism may hold only on a strict subset (sometimes, reduced to a single point) of the spectrum's domain., Comment: 31 pages, 5 figures; the statement of Theorem 2.5 has been simplified with new equivalent definitions of some parameters and is now easier to compare to those of Theorems 2.1 and 2.4. Also, the statements of Theorems 4.7 and 5.9 are more precise

Recently, a superconducting (SC) transition from low-field (LF) to high-field (HF) SC states was reported in CeRh$_2$As$_2$, indicating the existence of multiple SC states. It has been theoretically noted that the existence of two Ce sites in the unit cell, the so-called sub-lattice degrees of freedom owing to the local inversion symmetry breaking at the Ce sites, can lead to the appearance of multiple SC phases even under an interaction inducing spin-singlet superconductivity. CeRh$_2$As$_2$ is considered as the first example of multiple SC phases owing to this sub-lattice degree of freedom. However, microscopic information about the SC states has not yet been reported. In this study, we measured the SC spin susceptibility at two crystallographically inequivalent As sites using nuclear magnetic resonance for various magnetic fields. Our experimental results strongly indicate a spin-singlet state in both SC phases. In addition, the antiferromagnetic phase, which appears within the SC phase, only coexists with the LF SC phase; there is no sign of magnetic ordering in the HF SC phase. The present work reveals unique SC properties originating from the locally noncentrosymmetric characteristics., Comment: 9 pages, 7 figures, including Supplementary Materials, selected as Editors' Suggestion

We consider a general random walk loop soup which includes, or is related to, several models of interest, such as the Spin O(N) model, the double dimer model and the Bose gas. The analysis of this model is challenging because of the presence of spatial interactions between the loops. For this model it is known from Quitmann and Taggi (2022) that macroscopic loops occur in dimension three and higher when the inverse temperature is large enough. Our first result is that, on the $d$ dimensional lattice, the presence of repulsive interactions is responsible for a shift of the critical inverse temperature, which is strictly greater than $\frac{1}{2d}$, the critical value in the non interacting case. Our second result is that a positive density of microscopic loops exists for all values of the inverse temperature. This implies that, in the regime in which macroscopic loops are present, microscopic and macroscopic loops coexist. Moreover, we show that, even though the increase of the inverse temperature leads to an increase of the total loop length, the density of microscopic loops is uniformly bounded from above in the inverse temperature. Our last result is confined to the special case in which the random walk loop soup is the one associated to the Spin O(N) model with arbitrary integer values of $N \geq 2$ and states that, on $\mathbb{Z}^2$, the probability that two vertices are connected by a loop decays at least polynomially fast with their distance., Comment: 26 pages, 3 Figures

This paper is devoted to the mathematical modeling of a combined effect of directional and bulk crystallization in a phase transition layer with allowance for nucleation and evolution of newly born particles. We consider two models with and without fluctuations in crystal growth velocities, which are analytically solved using the saddle-point technique. The particle-size distribution function, solid-phase fraction in a supercooled two-phase layer, its thickness and permeability, solidification velocity, and desupercooling kinetics are defined. This solution enables us to characterize the mushy layer composition. We show that the region adjacent to the liquid phase is almost free of crystals and has a constant temperature gradient. Crystals undergo intense growth leading to fast mushy layer desupercooling in the middle of a two-phase region. The mushy region adjacent to the solid material is filled with the growing solid-phase structures and is almost desupercooled. © 2021 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons, Ltd. Russian Science Foundation, RSF: 21-79-10012 The authors gratefully acknowledge financial support from the Russian Science Foundation (project no. 21-79-10012). Open Access funding enabled and organized by Projekt DEAL.

Unformatted post-print version of the accepted article Solid-solid transitions in poly (hexamethylene carbonate) (PC6) and poly (octamethylene carbonate) (PC8), denoted δ to α transition, have been investigated, using self-nucleation and Successive Self-nucleation and Annealing (SSA) technique. The SSA protocol was performed in-situ for thermal (differential scanning calorimetry (DSC)), structural (Wide-angle X-ray Scattering (WAXS)), and conformational (Fourier-transformed Infrared Spectroscopy (FT-IR)) characterization. The final heating after SSA fractionation displayed an enhanced (compared to a standard second DSC heating scan) endothermic and unfractionated peak signal at low temperatures corresponding to the δ to α transition. The improved (i.e., higher enthalpy and temperature than in other crystallization conditions) δ to α transition signal is produced by annealing the thickest lamellae made up by α and β phase crystals after SSA treatment. As thicker lamellae are annealed, more significant changes are produced in the δ to α transition, demonstrating the transition dependence on crystal stability, thus, on the crystallization conditions. The ability of SSA to significantly enhance the observed solid-solid transitions makes it an ideal tool to detect and study this type of transitions. In-situ WAXS reveals that the δ to α transition corresponds to a change in the unit cell dimensions, evidenced by an increase in the d-spacing. This implies a more efficient chain packing in the crystal, for both samples, in the δ phase (lower d-spacing at low temperatures) than in the α phase (higher d-spacing at high temperatures). The chain packing differences are explained through in-situ FT-IR measurements that show the transition from ordered (δ phase) to disordered (α phase) methylene chain conformations. We would like to acknowledge financial support provided by the National Key R&D Program of China (2017YFE0117800) and the National Natural Science Foundation of China (51820105005, 21922308, and 52050410327). We also acknowledge financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 778092. This work has also received funding from MINECO through project MAT2017-83014-C2-1-P and from the Basque Government through grant IT1309-19. R.A.P.-C is supported by the China Postdoctoral Science Foundation (2020M670462). G.L. is grateful to the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Y201908). We also thank the BSRF (beamline 1W2A) for providing beamtime.

Multiple numerical studies have unambiguously shown the existence of a liquid-liquid critical point in supercooled states for different numerical models of water, and various structural indicators have been put forward to describe the transformation associated with this phase transition. Here we analyze numerical simulations of near-critical supercooled water to compare the behavior of several of such indicators with critical density fluctuations. We show that close to the critical point most indicators are strongly correlated to density, and some of them even display identical distributions of fluctuations. These indicators probe the exact same free energy landscape, therefore providing a thermodynamic description of critical super-cooled water which is identical to that provided by the density order parameter. This implies that close to the critical point, there is a tight coupling between many, only apparently distinct, structural degrees of freedom., The Journal of Physical Chemistry B, 127 (1), ISSN:1520-6106, ISSN:1520-5207, ISSN:1089-5647

An Rb2CoSi5O12 leucite analogue has been synthesized. An ambient temperature X-ray powder diffraction study shows that this analogue has the Pbca orthorhombic structure of Cs2CdSi5O12. A high temperature X-ray powder diffraction study on this analogue shows a Pbca orthorhombic to Pa3¯ cubic phase transition at 457 K. The Rb2CoSi5O12 unit cell volume initially decreases with increasing temperature on passing through this phase transition.

The propagation of chirality across scales is a common but poorly understood phenomenon in soft matter. In this work, we use computer simulations to study chiral monolayer assemblies formed by hard rod-like colloidal particles in the presence of non-adsorbing polymer and characterize the thermodynamic driving forces responsible for the twisting. Simulations show that straight (achiral) rods assemble into monolayers with a spontaneous twist that is either left- or right-handed, while helical (chiral) rods lead to assemblies with preferential chiral features that depend on their handedness and curliness. The onset of chirality in these monolayers can be traced back to small clusters formed at the initial stage of the self-assembly. In these microscopic monolayers, entropy drives twisting in ways that differ from the assumptions on which existing continuum theory is built. Depending on the geometry of the constituent rods, the preferred chiral twist can be driven by entropy gain of the polymers, or of the rods, or both. In addition, the variation of the polymer entropy with twist depends on changes in both the surface area and the volume of the monolayer. Rod fluctuations perpendicular to the monolayer also play an important role in stabilising the twisting., 14 pages, 12 figures

Membraneless organelles are droplets in the cytosol that are regulated by chemical reactions. Increasing studies suggest that they are internally organized. However, how these subcompartments are regulated remains elusive. Herein, we describe a complex coacervate-based model composed of two polyanions and a short peptide. With a chemical reaction cycle, we control the affinity of the peptide for the polyelectrolytes leading to distinct regimes inside the phase diagram. We study the transitions from one regime to another and identify new transitions that can only occur under kinetic control. Finally, we show that the chemical reaction cycle controls the liquidity of the droplets offering insights into how active processes inside cells play an important role in tuning the liquid state of membraneless organelles. Our work demonstrates that not only thermodynamic properties but also kinetics should be considered in the organization of multiple phases in droplets.

The article evaluates the energy resources of the components of the environment and the prospects for their use on the redistribution with the creation of local zones of cooling and heating. The physical basis of the principle and systems of redistribution and transformations of energy resources of environments with coverage of the role of compensation processes is given. The use of closed energy circuits with intermediate energy sources, which are subject to phase transitions of evaporation and condensation, and data of energy potentials of ambient air, which are practically achievable for use on this basis, is proposed. The article shows the advantages of arranging systems for redistribution of thermal potentials based on the use of phase transitions of material media. Determination of energy balances of energy redistribution systems is carried out with the indication that in the end, such a method is the most energy-efficient. Upon completion of technological tasks, local areas with different energy potentials and temperatures degrade in dissipation processes and transform to the level of environmental indicators. This means interfering with the environment only at the level of energy costs in compensation processes. The article shows the transition to secondary recovery systems of energy resources based on the use of primary energy sources in environmental transformations at the levels of increasing their energy potentials and providing phase transitions with appropriate mathematical formalizations. A regression analysis of the feasibility of using primary energy potentials is given. It is proved that in the heat pump due to the generated mechanical energy the heat return at the level of the lost one. The estimation of the general condition of processes at power effects is given. The offered air pump and system of realization of a refrigerating cycle are considered. The redistribution of energy potentials of natural, forcibly created environments or systems and the synthesis on this basis of powerful heat fluxes in combination with advanced control methods, allows you to control their values of thermodynamic parameters.

Dislocations present unique opportunities for nanostructuring advanced structural and functional materials due to the recent discoveries of linear complexions thermodynamically stable nanoscale features with unique chemistry and structure confined at dislocations. The formation of such features is driven by solute segregation near the dislocation core and results in the stabilization of dislocations, altering mechanical, thermodynamic, and transport properties of the final material. This perspective article gives an overview of the recent discoveries and predictions made by high-resolution experimental characterization techniques, as well as large-scale atomistic simulations in the newly emerging field of linear complexions.

Unformatted post-print version of the accepted article Poly (hexamethylene carbonate) (PC6) and poly (octamethylene carbonate) (PC8) were studied under different crystallization conditions. Using differential scanning calorimetry (DSC), a new solid-solid transition, denoted α to δ transition, was detected at low temperatures (

The study of states of arousal is key to understand the principles of consciousness. Yet, how different brain states emerge from the collective activity of brain regions remains unknown. Here, we studied the fMRI brain activity of monkeys during wakefulness and anesthesia-induced loss of consciousness. We showed that the coupling between each brain region and the rest of the cortex provides an efficient statistic to classify the two brain states. Based on this and other statistics, we estimated maximum entropy models to derive collective, macroscopic properties that quantify the system’s capabilities to produce work, to contain information, and to transmit it, which were all maximized in the awake state. The differences in these properties were consistent with a phase transition from critical dynamics in the awake state to supercritical dynamics in the anesthetized state. Moreover, information-theoretic measures identified those parameters that impacted the most the network dynamics. We found that changes in the state of consciousness primarily depended on changes in network couplings of insular, cingulate, and parietal cortices. Our findings suggest that the brain state transition underlying the loss of consciousness is predominantly driven by the uncoupling of specific brain regions from the rest of the network. A.P.A., B.J., and G.D. received funding from the FLAG-ERA JTC (PCI2018-092891). G.D. acknowledges funding from the European Union’s Horizon 2020 FET Flagship Human Brain Project under Grant Agreement 785907 HBP SGA1, SGA2, and SGA3, the Spanish Ministry Research Project PSI2016-75688-P (AEI/FEDER), the Catalan Research Group Support 2017 SGR 1545, and AWAKENING (PID2019-105772GB-I00, AEI FEDER EU) funded by the Spanish Ministry of Science, Innovation and Universities (MCIU), State Research Agency (AEI) and European Regional Development Funds (FEDER). M.L.K. is supported by the ERC Consolidator Grant: CAREGIVING (n. 615539), Center for Music in the Brain, funded by the Danish National Research Foundation (DNRF117), and Centre for Eudaimonia and Human Flourishing funded by the Pettit and Carlsberg Foundations. BJ received funding from Fondation Bettencourt-Schueller, Université Paris-Saclay (UVSQ), Fondation de France, Collège de France and from INSERM. CMS was supported by Comisión Nacional de Investigación Ciencia y Tecnología (CONICYT, currently ANID) through Programa Formacion de Capital Avanzado (PFCHA), Doctoral scholarship Becas Chile: CONICYT PFCHA/DOCTORADO BECAS CHILE/2016—72170507.

In condensed matter, phase separation is strongly related to ferroelasticity, ferroelectricity, ferromagnetism, electron correlation, and crystallography. These ferroics are important for nano-electronic devices such as non-volatile memory. However, the quantitative information regarding the lattice (atomic) structure at the border of phase separation is unclear in many cases. Thus, to design electronic devices on the molecular level, a quantitative relationship must be established between the lattice and the electrons. Herein, we elucidated a PdII–PdIV/PdIII–PdIII phase transition and phase separation mechanism for [Pd(cptn)2Br]Br2 (cptn = 1R,2R-diaminocyclopentane), propagated through a hydrogen-bonding network. Although the Pd···Pd distance was used to determine the electronic state, the differences in the Pd···Pd distance and the optical gap between Mott–Hubbard (MH) and charge-density-wave (CDW) states were only 0.012 Å and 0.17 eV, respectively. The N–H···Br···H–N hydrogen-bonding network functioned as a jack, adjusting the structural difference dynamically, and allowing visible ferroelastic phase transition/separation in a fluctuating N2 gas flow. In addition, the effect of the phase separation on the spin susceptibility and electrical conductivity were clarified to represent the quasi-epitaxial crystals among CDW–MH states. These results indicate that the phase transitions and separations could be controlled via modifications at the atomic and molecular levels, such as the addition of hydrogen bonding.

Bulk nanomaterials with an open porosity offer exciting prospects for creating new functional materials for various applications in photonics, IR-THz optics, metamaterials, heterogeneous photocatalysis, monitoring and cleaning toxic impurities in the environment. However, their availability is limited by the complexity of controlling the process of synthesis of bulk 3D nanostructures with desired physicochemical and functional properties. In this paper, we performed a detailed analysis of influence of a silica monolayer chemically deposited on the surface of a monolithic ultraporous nanostructure, consisting of a 3D nanofibril network of aluminum oxyhydroxide, on the evolution of structure and morphology, chemical composition and phase transformations after heat treatment in the temperature range of 20−1700 °C. The experimental results are interpreted in the framework of a physical model taking into account surface and volume mass transport and sintering kinetics of nanofibrils, which made it possible to estimate activation energies of the surface diffusion and sintering processes. It is shown that the presence of a surface silica monolayer on the surface affects the kinetics of aluminum oxyhydroxide dehydration and inhibits diffusion mass transfer and structural phase transformations. As a result, the overall evolution of the 3D nanostructure significantly differs from that of nanomaterials without surface chemical modification.

Crystallographic relationships between α- and β-phases resulting from phase transformations, which took place during the continuous water quenching (WQ), air cooling (AC) and furnace cooling (FC) of a Ti6Al4V plates solution treated at 1065 °C, were investigated by methods of electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). WQ, AC and FC resulted in typical martensite, basket-weave and parallel-plate Widmanstatten structures, respectively. The experimental distribution of α/β-misorientations deviated from BOR at set discrete angles close to 22, 30, 35 and 43°. The experimental spectra of angles were confirmed by theoretical calculations of the possible misorientations between the α and β phases through the βo→α→βII –transformation path based on Burgers orientation relationship (BOR). Joint analysis of the experimental data and theoretical calculations revealed that the secondary βII-phase was precipitated according to the sequence βo→α→βII during continuous cooling from the single-phase β-region. Similar spectra for α/β-phase misorientations for all investigated cooling rates acknowledged the similar transformation mechanisms and dominant shear component of the phase transformations. © 2022 by the authors. Ministry of Education and Science of the Russian Federation, Minobrnauka This research was funded by the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program).

Four ionic liquids (ILs) based on the bis(trifluoromethanesulfonyl)imide (NTf2) anion were synthesized and characterized concerning their thermal stability, the occurrence of low temperature phase transitions and their volatility. All these physical quantities are highly important for possible applications. Both monocationic and dicationic ILs were considered. All ILs exhibit thermal stability exceeding 350 °C, an extremely high value, due to the presence of the NTf2 anion. Monocationic ILs can undergo crystallization, and they melt at 1 and 38 °C. On the contrary, dicationic ILs containing large positively charged ions display only a glass transition around −40 °C, without any crystallization or melting process; this fact is particularly important in view of the possibly low temperature applications of the dication ILs. The vapor pressure, pv, of the four ILs was measured by isothermal thermogravimetry in the temperature range between 250 and 325 °C; the lowest values of pv were obtained for the two dicationic liquids, suggesting that they are particularly well suited for high temperature applications. The vaporization enthalpy was calculated through the Clausius–Clapeyron equation and was found in the range between ~140 and ~180 kJ/mol depending on the specific IL.

American mineralogist 105, 1-35 (2020). doi:10.2138/am-2021-7621, Minerals formed at high pressures are sensitive indicators of extreme pressure-temperature conditions that occur in nature. The discovery of the high-pressure polymorph of (Fe,Ni)$_2$P, allabogdanite in the surficial pyrometamorphic rocks of the Hatrurim Formation (the Mottled Zone) surrounding the Dead Sea basin in Israel is the first terrestrial occurrence of a mineral previously only found in iron meteorites. Stepwise annealing experiments demonstrate that allabogdanite is metastable at ambient pressure and that it irreversibly transforms into its low-pressure polymorph, barringerite, upon heating to 850±50°C. High-pressure high-temperature diamond-anvil cell (DAC) experiments confirm the results of annealing experiments. The DAC data indicate that Hatrurim allabogdanite is metastable below 7.4 GPa, and the low- to high-pressure phase transition (barringerite→allabogdanite) occurs at 25±3 GPa and 1400±100°C. The observed transition pressure of Hatrurim allabogdanite is significantly higher than that of pure synthetic Fe$_2$P (8 GPa), due to partial substitution of Fe for Ni (4 wt.%) and Mo (2.5 wt.%). Because the influence of substituting impurities on the conditions of phase transitions can be unexpectedly strong, our findings confirm that caution should be exercised when extrapolating data from experiments on synthetic compounds to natural systems. Based on the discovery of terrestrial allabogdanite (Fe,Ni)$_2$P coupled with experiments probing the phase transitions in this natural composition, we contend that terrestrial allabogdanite formed via transformation from barringerite and posit potential scenarios of its formation., Published by GeoScienceWorld, Alexandria, Va.

In conventional disorder–order phase transitions, a system shifts from a highly symmetric state, where all states are equally accessible (disorder) to a less symmetric state with a limited number of available states (order). This transition may occur by varying a control parameter that represents the intrinsic noise of the system. It has been suggested that stem cell differentiation can be considered as a sequence of such symmetry-breaking events. Pluripotent stem cells, with their capacity to develop into any specialized cell type, are considered highly symmetric systems. In contrast, differentiated cells have lower symmetry, as they can only carry out a limited number of functions. For this hypothesis to be valid, differentiation should emerge collectively in stem cell populations. Additionally, such populations must have the ability to self-regulate intrinsic noise and navigate through a critical point where spontaneous symmetry breaking (differentiation) occurs. This study presents a mean-field model for stem cell populations that considers the interplay of cell–cell cooperativity, cell-to-cell variability, and finite-size effects. By introducing a feedback mechanism to control intrinsic noise, the model can self-tune through different bifurcation points, facilitating spontaneous symmetry breaking. Standard stability analysis showed that the system can potentially differentiate into several cell types mathematically expressed as stable nodes and limit cycles. The existence of a Hopf bifurcation in our model is discussed in light of stem cell differentiation.

Hybrid organic–inorganic iodides based on Bi(III) and Sb(III) provide integrated functionalities through the combination of high dielectric constants, semiconducting properties and ferroic phases. Here, we report a pyrrolidinium-based bismuth (1) and antimony (2) iodides of (NC4H10)3[M2I9] (M: Bi(III), Sb(III)) formula which are ferroelastic at room temperature. The narrow band gaps (~2.12 eV for 1 and 2.19 eV for 2) and DOS calculations indicate the semiconducting characteristics of both materials. The crystal structure consists of discrete, face-sharing bioctahedra [M2I9]3− and disordered pyrrolidinium amines providing charge balance and acting as spacers between inorganic moieties. At room temperature, 1 and 2 accommodate orthorhombic Cmcm symmetry. 1 displays a complex temperature-induced polymorphism. It is stable up to 525 K and undergoes a sequence of low-temperature phase transitions (PTs) at 221/222 K (I ↔ II) and 189/190 K (II ↔ III) and at 131 K (IV→III), associated with the ordering of pyrrolidinium cations and resulting in Cmcm symmetry breaking. 2 undergoes only one PT at T = 215 K. The dielectric studies disclose a relaxation process in the kilohertz frequency region, assigned to the dynamics of organic cations, described well by the Cole–Cole relation. A combination of single-crystal X-ray diffraction, synchrotron powder diffraction, spin–lattice relaxation time of 1H NMR, dielectric and calorimetric studies is used to determine the structural phase diagram, cation dynamics and electric properties of (NC4H10)3[M2I9].

A model is developed for the directional solidification of a binary melt with a two-phase zone (mushy zone), where the fraction of the liquid phase is described by a space–time scaling relation. Self-similar variables are introduced and the interphase boundary growth is inversely proportional to the square root of time. The mathematical model of the process is reformulated using self-similar variables. Exact self-similar solutions of heat-and-mass transfer equations are determined in the presence of two mobile phase-transition boundaries, namely, solid–mushy zone and mushy zone–liquid ones. The temperature and impurity concentration distributions in the solid phase, the mushy zone, and the melt are found as integral expressions. A decrease in the dimensionless cooled-boundary temperature leads to an increase in the solidification rate and the fraction of the liquid phase. The solidification rate, the parabolic growth constants, and the fraction of the liquid phase at the solid–mushy zone boundary are determined depending on the scaling parameter and the thermophysical constants of the solidifying melt. The positions of the solid–mushy zone and mushy zone–binary melt phase transition boundaries are found. The dependences of the solidification rate (inversely proportional to the square root of time) are analyzed. The scaling parameter significantly is shown to substantially affect the solidification rate and the fraction of the liquid phase in the phase transformation region. The developed model and the method of its solution can be generalized to the case of directional solidification of multicomponent melts in the presence of several phase transformation regions (e.g., main and cotectic two-phase zones during the solidification of three-component melts). © 2021, Pleiades Publishing, Ltd. This work was supported by the Russian Foundation for Basic Research (project no. 18-58-00034 Bel_a) and the Belarussian Foundation for Basic Research (project no. F18R-195).

Diphenylalanine (FF) demonstrates a robust ability to self‐assemble at the nanoscale forming a variety of structures ranging from nanospheres to nano‐ and microtubes resulting in outstanding functional properties including pyro‐ and piezoelectricity. FF nanotubes mimic the structure of β‐amyloid fibrils characteristic of Alzheimer's disease and thus can serve as a model material in biology and medicine. In this work, we report experimental proof that water trapped inside nanotubes exhibits dielectric properties similar to that of bulk water despite being confined in an ∼1 nm internal cavity. FF peptides thus provide a suitable template for the stabilization of the tetrahedral configuration of bulk water. Several phase transitions were observed via broadband dielectric spectroscopy and differential scanning calorimetry. Of these, two glass transitions at 205 K and 133 K related to different phases of water were found. The presence of α‐relaxation in the so‐called “no man's land” leads to a global glass transition at Tg = 133 K and structural phase transition at 230 K characteristic of tetrahedral water. The characterized collective response of water dipoles to an external electric field renders high pyro‐ and piezoelectric activity and non‐linear optical effects in FF dipeptides, conferring polarization‐dependent functionality to this important class of biomaterials.

In this work, we studied the mechanical and thermal stability of ~100 nm Pd thin films magnetron sputter deposited on a bare oxidized Si(100) wafer, a sputtered Titanium (Ti) intermediate layer, and a spin-coated Polyimide (PI) intermediate layer. The dependence of the film stability on the film morphology and the film-substrate interaction was investigated. It was shown that a columnar morphology with elongated voids at part of the grain boundaries is resistant to embrittlement induced by the hydride formation (α↔β phase transitions). For compact film morphology, depending on the rigidity of the intermediate layer and the adherence to the substrate, complete transformation (Pd-PI-SiO2/Si) or partly suppression (Pd-Ti-SiO2/Si) of the α to β-phase was observed. In the case of Pd without intermediate layer (Pd-SiO2/Si), buckling delamination occurred. The damage and deformation mechanisms could be understood by the analysis of the stresses and dislocation (defects) behavior near grain boundaries and the film-substrate interface. From diffraction line-broadening combined with microscopy analysis, we showed that in Pd thin films, stresses relax at critical stress values via different relaxation pathways depending on film-microstructure and film-substrate interaction. On the basis of the in-situ hydriding experiments, it was concluded that a Pd film on a flexible PI intermediate layer exhibits free-standing film-like behavior besides being strongly clamped on a stiff SiO2/Si substrate.

Midiendo la resistencia eléctrica del electrolito sólido NaI-AgI, se mostró que al adicionar NaI al AgI se estabiliza la transición de la fase conductora iónica (β-AgI) a la fase superiónica (α-AgI) a 420 K al incrementar la temperatura. La conductividad iónica en la transición β → α del AgI aumenta varios órdenes de magnitud. Para simular esta transición, se consideró un modelo fenomenológico basado en una densidad de energía libre, siendo la concentración de defectos en equilibrio (n) el parámetro de orden e interpretando éste como el inverso de la resistencia R. Los datos experimentales se ajustaron muy bien al modelo propuesto. Electrical resistance measurements of NaI-AgI solid electrolyte showed that adding NaI to AgI stabilizes the transition from conducting ionic phase (β-AgI) to the superionic (α-AgI) at 420 K with increasing temperature. The ionic conductivity at the β → α transition of AgI increases by several orders of magnitude. Considering a phenomenological model based on a free energy density was fitted the abrupt jump of ionic conductivity. In this model, the equilibrium defect concentration (, R is the resistance) is the order parameter. Better results are achieved for the order parameter.

A chiral Eu(III) coordination polymer with phase-transition behavior, [Eu(+tfc)3(m-dpeb)]n, (+tfc: (+)-3-trifluoroacetylcamphorato, m-dpeb: 1,3-bis(diphenylphosphorylethynyl)benzene) was reported for understanding the effect of polymer chain arrangement (orientation effect) on the circularly polarized luminescence (CPL) in a solid system. The phase-transition behavior of the transformable Eu(III) coordination polymer was characterized using differential scanning calorimetry and powder X-ray diffraction. The Eu(III) coordination polymer exhibited phase transition at approximately 180 degrees C. The magnitude of the CPL intensity was drastically changed because of the phase transition, without coordination geometrical change around the Eu(III) ion. In this study, the orientation effect of a chiral Eu(III) coordination polymer on the CPL properties in crystalline solid is demonstrated.

To offer a response to the increasing interest on high-temperature shape memory alloys, mainly driven by the aeronautic and aerospace industries, the design and characterization of Cu-Al-Ni shape memory alloys with high transformation temperatures, between 373 K and 473 K, are approached. The present alloy design is based on the transformation from cubic β3 austenite to the monoclinic β'3 martensite, which offers the advantage of exhibiting not only higher transformation temperatures but also a thermal hysteresis of about 12 K, much smaller than the orthorhombic γ'3 martensite historically considered for this alloy system. The influence of the alloy concentration and the thermal treatments, on the martensitic transformation temperatures is systematically analyzed and a quantitative and predictive equation is proposed. The influence of the stress on the transformation was also studied under two experimental conditions: at constant stress as a function of temperature (shape memory effect) and at constant temperature as a function of the stress (superelastic effect). A double stress-induced transformation from β3 to β'3 and α'3 with an outstanding reversible and reproducible 24% superelastic strain is also reported. The experimental results allows also determine the Clausius-Clapeyron diagrams for this series of alloys, as a fundamental tool for further design of sensing and actuating devices based on these high-temperature shape memory alloys.

Monocrystals (N(CH3)4)2MnCl4were grown from an aqueous solution of salts by slow evaporation at room temperature. The effect of phase transitions on the behavior of photoluminescence spectra, as well as excitation spectra and time of attenuation of the glow band of 539nm is studied in the temperature range of 4.5‒300K. Based on the studies of the spectra of photoluminescence of the (N(CH3)4)2MnCl4, the glow bands, which are caused by the glow of the Mn2+ion and correspond to the4Т1→6А1transition, were determined. The temperature evolution of photoluminescence spectra (4.5–300K) of the (N(CH3)4)2MnCl4crystal demonstrates anomalies of their parameters at the points of phase transitions. Temperature dependences of crystal photoluminescence spectra of the (N(CH3)4)2MnCl4crystal prove the existence of phase transitions in the temperature intervals from 100 to 300K. The excitation spectra for the luminescence band of 539nm and their temperature evolution (4.5–300K) are shown. The bands of around 2.93 and 2.96eV are quickly damped with temperature, so at the temperatures above 170K and 270K, the bands of 2.96 and 2.93eV are not observed, respectively. Peaks in the excitation spectrum correspond to electron transitions from the basic state of6A1Mn2+to various excited states (Td). Their excitation energies are explained by a model of crystals using the Tanabe-Sugano diagrams. The Racah B and C parameters, as well as the splitting of crystal field Δ, were calculated based on the Tanabe-Sugano diagrams for d5of electronic configuration. The temperature behavior of the time of attenuation of the photoluminescence band of 539µm was studied. The resulting time of attenuation of the photoluminescence band increases at an increase in temperature. The kinetics of attenuation of the photoluminescence band of 539µm of a crystal is well described by an exponential function

The zinc aspartate complex, commonly used as a dietary supplement, crystallizes as either the dihydrate or the sesquihydrate. High pressure favours the sesquihydrate, and this has been rationalized by measurements of the compressibility using single-crystal X-ray diffraction up to 4 GPa., The zinc aspartate (ZnAsp2) complex, a common dietary supplement, preferentially crystallizes as the dihydrate (ZnAsp2·2H2O) from aqueous solution. Under normal conditions the dihydrate easily transforms into the sesquihydrate (ZnAsp2·1.5H2O). The dihydrate crystal structure is triclinic, space group P 1, and the sesquihydrate is monoclinic, space group C2/c. However, their structures are closely related and similarly consist of zinc aspartate ribbons parallel to pores accommodating water molecules. These porous structures can breathe water molecules in and out depending on the temperature and air humidity. High pressure above 50 MPa favours the sesquihydrate, as shown by recrystallizations under pressure and compressibility measured by single-crystal X-ray diffraction up to 4 GPa. This preference is explained by the reduced volume of the sesquihydrate and water compressed separately, compared with the dihydrate. The sesquihydrate undergoes an isostructural phase transition when the voids collapse at 0.8 GPa, whereas no phase transitions occur in the dihydrate, because its pores are supported by increased water content.

We study noise-induced transformations in the two-age structured population model with the Allee effect and environmental fluctuations. In this bistable model, ecological shifts are associated mathematically with random transitions between basins of coexisting attractors. The following phenomena are revealed and studied: (i) noise-induced extinction, (ii) stochastic regeneration, and (iii) excitement of random mixed-mode oscillations. Constructive abilities of the analytical method of confidence domains are demonstrated in the parametric study of these phenomena.

A series of Ti–30Zr alloys have been synthesized by the spark plasma sintering (SPS) process using a mixture of elemental powders processed by mechanical alloying. A sintering temperature of 900 °C was used during SPS with heating rates of 140, 200 and 350 °C min−1 with a constant load of 50 MPa. The effect of the heating rate on the densification, microstructure, phase transformation and microhardness is discussed. The sintering kinetics and the in situ densification were performed by the analysis of the punch displacement during SPS processing. Structural details of consolidated materials were evaluated by the combination of X-ray diffraction, field emission scanning electron microscopy and differential scanning calorimetry tests. Vickers microhardness of samples was also evaluated. The results show that samples reached high densification values up to 99.7% of the relative density by using lower sintering temperatures in comparison to conventional sintering techniques. Phase transformation analysis demonstrates the formation of αʹʹ and ω metastable phases without using any post-treatment. Microhardness values between 950 and 1040 HV were obtained as an effect of the SPS parameters and metastable phase precipitations.

The crystalline‐to‐vitreous phase transformation of a SiO2 bilayer supported on Ru(0001) was studied by time‐dependent LEED, local XPS, and DFT calculations. The silica bilayer system has parallels to 3D silica glass and can be used to understand the mechanism of the disorder transition. DFT simulations show that the formation of a Stone–Wales‐type of defect follows a complex mechanism, where the two layers show decoupled behavior in terms of chemical bond rearrangements. The calculated activation energy of the rate‐determining step for the formation of a Stone—Wales‐type of defect (4.3 eV) agrees with the experimental value. Charge transfer between SiO2 bilayer and Ru(0001) support lowers the activation energy for breaking the Si−O bond compared to the unsupported film. Pre‐exponential factors obtained in UHV and in O2 atmospheres differ significantly, suggesting that the interfacial ORu underneath the SiO2 bilayer plays a role on how the disordering propagates within the film., Real‐time studies of the crystalline‐to‐vitreous conversion rate of a SiO2 bilayer supported on Ru(0001) reveal an apparent activation energy of 4.2 eV for the process. DFT simulations suggest the formation of a Stone–Wales‐type defect as the starting point for the transformation.

We investigate the strong out-of-equilibrium dynamics occurring when a harmonically trapped ultracold bosonic gas is evaporatively cooled across the Bose--Einstein condensation transition. By imaging the cloud after free expansion, we study how the cooling rate affects the timescales for the growth of the condensate order parameter and the relaxation dynamics of its spatial fluctuations. We find evidence of a delay on the condensate formation related to the collisional properties and a universal condensate growth following the cooling rate. Finally, we measure an exponential relaxation of the spatial fluctuations of the order parameter that also shows a universal scaling. Notably, the scaling for the condensate growth and for the relaxation of its fluctuations follow different power laws., Comment: 10 pages, 6 figures

31 p.-7 fig., The cellular interior is composed of a variety of microenvironments defined by distinct local compositions and composition-dependent intermolecular interactions.We review the various types of nonspecific interactions between proteins and between proteins and other macromolecules and supramolec ular structures that influence the state of association and functional prop erties of a given protein existing within a particular microenvironment at a particular point in time. The present state of knowledge is summarized, and suggestions for fruitful directions of research are offered., G.R.’s research is supported by Spanish Government Grant PID2019-104544GB-I00. A.P.M.’s research is supported by the Intramural Research Program, National Institute of Diabetes and Digestive and Kidney Diseases, NIH.

Domain walls in Cu–Cl boracite develop as a consequence of an improper ferroelastic, improper ferroelectric transition, and have attracted close interest because some are conductive and all can be mechanically written and repositioned by application of an electric field. The phase transition and its associated dynamical properties have been analysed here from the perspective of strain and elasticity. Determination of spontaneous strains from published lattice parameter data has allowed the equilibrium long-range order parameter for F 4 ̄ 3c → Pca21 to be modelled simply as being close to the order–disorder limit. High acoustic loss in the cubic phase, revealed by resonant ultrasound spectroscopy, is consistent with the presence of dynamical microdomains of the orthorhombic structure with relaxation times in the vicinity of ∼10−5–10−6 s. Low acoustic loss in the stability field of the orthorhombic structure signifies, on the other hand, that ferroelastic twin walls which develop as a consequence of the order–disorder process are immobile on this time scale. A Debye loss peak accompanied by ∼1% elastic stiffening at ∼40 K is indicative of some freezing of defects which couple with strain or of some more intrinsic freezing process. The activation energy of ⩾∼0.01–0.02 eV implies a mechanism which could involve strain relaxation clouds around local ferroelectric dipoles or freezing of polarons that determine the conductivity of twin walls.

We study the computational complexity of estimating local observables for Gibbs distributions. A simple combinatorial example is the average size of an independent set in a graph. A recent work of Galanis et al (2021) established NP-hardness of approximating the average size of an independent set utilizing hardness of the corresponding optimization problem and the related phase transition behavior. We instead consider settings where the underlying optimization problem is easily solvable. Our main contribution is to classify the complexity of approximating a wide class of observables via a generic reduction from approximate counting to the problem of estimating local observables. The key idea is to use the observables to interpolate the counting problem. Using this new approach, we are able to study observables on bipartite graphs where the underlying optimization problem is easy but the counting problem is believed to be hard. The most-well studied class of graphs that was excluded from previous hardness results were bipartite graphs. We establish hardness for estimating the average size of the independent set in bipartite graphs of maximum degree 6; more generally, we show tight hardness results for general vertex-edge observables for antiferromagnetic 2-spin systems on bipartite graphs. Our techniques go beyond 2-spin systems, and for the ferromagnetic Potts model we establish hardness of approximating the number of monochromatic edges in the same region as known hardness of approximate counting results., LIPIcs, Vol. 229, 49th International Colloquium on Automata, Languages, and Programming (ICALP 2022), pages 63:1-63:18

Several nanocomposites were prepared by extrusion from a commercial metallocene-type isotactic polypropylene (iPP) and different amounts of two types of graphene (G) nanofibers: ones with a high specific surface, named GHS, and the others with a low specific surface, labeled as GLS. The number of graphene layers was found to be around eight for GLS and about five in the GHS. Scanning electron microscopy (SEM) images of the resultant iPP nanocomposites showed a better homogeneity in the dispersion of the GLS nanofibers within the polymeric matrix compared with the distribution observed for the GHS ones. Crystallinity in the nanocomposites turned out to be dependent upon graphene content and upon thermal treatment applied during film preparation, the effect of the nature of the nanofiber being negligible. Graphene exerted a noticeable nucleating effect in the iPP crystallization. Furthermore, thermal stability was enlarged, shifting to higher temperatures, with increasing nanofiber amount. The mechanical response changed significantly with nanofiber type, along with its content, together with the thermal treatment applied to the nanocomposites. Features of nanofiber surface played a key role in the ultimate properties related to superficial and bulk stiffness., This work was supported by the Agencia Estatal de Investigación (AEI, Spain) (grant number PID2020-114930GB-I00).

We derive an arbitrary-gauge criterion under which condensed matter within an electromagnetic field may transition to a photon condensed phase. Previous results are recovered by selecting the Coulomb-gauge wherein photon condensation can only occur for a spatially-varying field and can be interpreted as a magnetic instability. We demonstrate the gauge-invariance of our description directly, but since matter and photons are gauge-relative concepts we find more generally that photon condensation can occur within a spatially uniform field, and that the relative extent to which the instability is both magnetic and electric versus purely magnetic depends on the gauge., Comment: 7 pages (plus appendices). V2 contains revised discussion of the results and more detailed consideration of symmetries

A plethora of temperature induced phase transitions have been observed in $[CH_3NH_3][M(HCOO)_3]$ compounds, where M is Co(II) or Ni(II). Among them, the nickel compound exhibits a combination of magnetic and nuclear incommensurabil-ity below N\'eel temperature. Despite the fact that the zero-field behavior has been previously addressed, here we study in depth the macroscopic magnetic behavior of this compound to unveil the origin of the atypical magnetic response found in it and in its parent family of formate perovskites. In particular, they show a puzzling magnetization reversal in the curves measured starting from low temperatures, after cooling under zero field. The first atypical phenomena is the im-possibility of reaching zero magnetization, even by nullifying the applied external field and even compensating it for the influence earth's magnetic field. Relatively large magnetic fields are needed to switch the magnetization from negative to positive values or vice versa, which is compatible with a soft-ferromagnetic system. The atypical path found in its first magnetization curve and hysteresis loop at low temperatures is the most noticeable feature. The magnetization curve switches from more than 1200 Oe from the first magnetization loop to the subsequent magnetization loops. A feature that cannot be explained using a model based on unbalanced pair of domains. As a result, we decipher this behavior in light of the incommensurate structure of this material. We propose, in particular, that the applied magnetic field induces a mag-netic phase transition from a magnetically incommensurate structure to a magnetically commensurate structure., Comment: 9 pages, 7 figures, 1 table

The strength and dynamics of magnetoelastic coupling through the paramagnetic (PM) – antiferromagnetic (AFM) – ferrimagnetic (FIM) transitions in multiferroic hexagonal ErMnO3 have been investigated by Resonant Ultrasound Spectroscopy. Elastic stiffening by up to 2% below the PM – AFM transition at 80 K arises from biquadratic coupling between strain and the magnetic order parameter with relaxation times longer than ~10-6 s for the response of spins to changes in strain. In contrast with YMnO3, the PM – AFM transition in ErMnO3 is accompanied by a peak in acoustic loss immediately below the Néel point which is interpreted in terms of strain relaxation accompanying ordering of spins of Er3+ at 4b sites. Changes in the magnetic ordering scheme at the AFM – FIM transition near 3 K are accompanied by elastic softening of ~0.03 %. Poling of the low temperature ferrimagnetic structure round magnetic hysteresis loops is detected as small changes in elastic stiffness which arise due to the contribution of piezomagnetic and/or piezoelectric moduli. Contributions of piezoelectric moduli to acoustic resonance frequencies also permit changes in the configuration of ferroelectric domains to be detected in response both to cycling through this transition and to application of a magnetic field. A peak in acoustic loss in the vicinity of 250 K is attributed to strain-mediated pinning/freezing of some aspect of the domain microstructure with an activation energy of ~0.25-0.3 eV. A return to the original elastic properties on heating to temperatures above ~250 K is interpreted in terms of backswitching of domains to the configuration they had at the start. These observations confirm the existence of subtle variations in magnetoelastic coupling behaviour relating to both the magnetic order parameters and magnetic domain structures.

We report the results of Raman spectroscopy high-pressure studies of alkali metal fluoroargentates (M2AgF4, where M=Na, K, Rb) associated with theoretical and x-ray diffraction studies for the K member of the series. Theoretical density functional calculations predict two structural phase transitions for K2AgF4: one from low pressure monoclinic P21/c (beta) phase to intermediate-pressure tetragonal I4!2d structure at 6 GPa, and another to high-pressure triclinic P1! phase at 58 GPa. However, Raman spectroscopy and X-ray diffraction data indicate that both polymorphic forms of K2AgF4 as well as two other fluoroargentate phases studied undergo amorphization at pressure as low as several GPa., Comment: 12 pages, 4 figures, plus electronic supplement

We employ the recently introduced generalized microcanonical inflection point method for the statistical analysis of phase transitions in flexible and semiflexible polymers and study the impact of the bending stiffness upon the character and order of transitions between random-coil, globules, and pseudocrystalline conformations. The high-accuracy estimates of the microcanonical entropy and its derivatives required for this study were obtained by extensive replica-exchange Monte Carlo simulations. We observe that the transition behavior into the compact phases changes qualitatively with increasing bending stiffness. Whereas the &Theta, collapse transition is less affected, the first-order liquid-solid transition characteristic for flexible polymers ceases to exist once bending effects dominate over attractive monomer-monomer interactions.

This data set contains early warning signal statistics computed from CMIP5 climate simulations used to test the model presented in our paper "Universal Early Warning Signals of Phase Transitions in Climate Systems" Data is selected and preprocessed as outlined in the paper. For 8 models in the CMIP5 repository, abrupt transitions are identified using the edge detection results of Bathiany et. al. (variables/locations with highest abruptness scores are included, as well as null time series with abruptness scores below a set threshold). Spatiotemporal time data for each of these instances is processed as follows: Data provided at monthly resolution is separated into twelve time series sampled annually, in accordance with the processing carried out by Bathiany et. al. Runs are truncated such that they end at the time of abrupt transition (or randomly with the same length distribution, for null runs) Data is smoothed along the temporal axis using a Gaussian filter with kernel width \(\sigma = 96\) time steps. Data is normalized to zero mean and unit variance Twelve early warning indicator statistics are computed for each spatiotemporal time series: Temporal variance Temporal skewness Temporal kurtosis Temporal lag-1 autocorrelation Temporal lag-2 autocorrelation Temporal lag-3 autocorrelation Spatial variance Spatial skewness Spatial kurtosis Spatial distance-1 autocorrelation Spatial distance-2 autocorrelation Spatial distance-3 autocorrelation Temporal statistics are computed for each spatial grid point (on a sliding window) and then averaged into a single scalar time series Spatial statistics are computed separately for each time snapshot Results are presented in .pkl files formatted for Python Pandas. Each time series ('x' field) has dimension n*12, where n is the length of the time series (up to 600 steps). Other data fields are as follows: x Time series (in 12 dimensions) of EWS indicator statistics model CMIP5 model name cvar CMIP5 variable name table CMIP5 table name month Month sampled (integer 1-12) lat Latitude of sample location lon Longitude of sample location sample_loc Indices of sample location (based on CMIP5 data grid) sample_loc_meta Indices of sample location (based on Bathiany et. al. results) run_length Length of time series (number of time steps) t_roll_window Length of rolling window used to compute temporal EWS (in time steps) nan_pattern Boolean grid indicating which (if any) spatial coordinates contain missing data filter_fw Spatial size of region surrounding geographic location from which data is sampled (filter_fw = 9 means a 9x9 grid centered on sample_loc) null Boolean indicating whether the run corresponds to an observed abrupt transition (null = 0) or a low-abruptness control run (null = 1) Climate simulations from the CMIP5 collaboration are made available by the World Climate Research Programme and the Program for Climate Model Diagnosis & Intercomparison. Use of this data is subject to the terms outlined at https://pcmdi.llnl.gov/mips/cmip5/terms-of-use.html. Original CMIP5 data can be accessed through the ESGF data portals (see https://esgf-node.llnl.gov/projects/esgf-llnl or the project page at https://esgf-node.llnl.gov/search/cmip5).

There is an international consensus that reductions of CO2 emissions are needed in order to reduce global warming. So far, underground aquifer storage of CO2 is the only commercially active option, and it has been so since 1996, when STAOIL started injecting a million tons of CO2 per year into the Utsira formation. Storage of CO2 in the form of solid hydrate is another option that is safer. Injection of CO2 into CH4 hydrate-filled sediments can lead to an exchange in which the in situ CH4 hydrate dissociates and releases CH4. Two types of additives are needed, however, to make this exchange feasible. The primary objective of the first additive is related to hydrodynamics and the need to increase injection gas permeability relative to injection of pure CO2. This type of additive is typically added in amounts resulting in concentration ranges of additive in the order of tens of percentages of CO2/additive mixture. These additives will, therefore, have impact on the thermodynamic properties of the CO2 in the mixture. A second additive is added in order to reduce the blocking of pores by new hydrates created from the injection gas and free pore water. The second additive is a surfactant and is normally added in ppm amounts to the gas mixture. A typical choice for the first additive has been N2. The simple reasons for that are the substantial change in rheological properties for the injection gas mixture and a limited, but still significant, stabilization of the small cavities of structure I. There are, however, thermodynamic limitations related to adding N2 to the CO2. In this work, we discuss a systematic and consistent method for the evaluation of the feasibility of CO2 injection into CH4 hydrate-filled reservoirs. The method consists of four thermodynamic criterions derived from the first and second laws of thermodynamics. An important goal is that utilization of this method can save money in experimental planning by avoiding the design of CO2 injection mixtures that are not expected to work based on fundamental thermodynamic principles. The scheme is applied to hydrates in the Black Sea. Without compositional information and the knowledge that there is some verified H2S in some sites, we illustrate that the observed bottom hydrate stability limits are all with hydrate stability limits of hydrates containing from 0 to 3 mole% H2S. A limited number of different injection gas mixtures has been examined, and the optimum injection gas composition of 70 mole% CO2, 20 mole% N2, 5 mole% CH4, and 5 mole% C2H6 is feasible. In addition, a surfactant mixture is needed to reduce blocking hydrate films from injection gas hydrate.

Chemical transformations, such as ion exchange, are commonly employed to modify nanocrystal compositions. Yet the mechanisms of these transformations, which often operate far from equilibrium and entail mixing diverse chemical species, remain poorly understood. Here we explore an idealized model for ion exchange in which a chemical potential drives compositional defects to accumulate at a crystals surface. These impurities subsequently diffuse inward. We find that the nature of interactions between sites in a compositionally impure crystal strongly impacts exchange trajectories. In particular, elastic deformations which accompany lattice-mismatched species promote spatially modulated patterns in the composition. These same patterns can be produced at equilibrium in core/shell nanocrystals, whose structure mimics transient motifs observed in nonequilibrium trajectories. Moreover, the core of such nanocrystals undergoes a phase transition-from modulated to unstructured-as the thickness or stiffness of the shell is decreased. Our results help explain the varied patterns observed in heterostructured nanocrystals produced by ion exchange and suggest principles for the rational design of compositionally patterned nanomaterials.