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Phase field modeling and computer simulations were conducted to uncover the fundamental mechanism behind the peak in damping capacity observed in BaTiO3-reinforced composites, considering both insulating and conductive cases. The damping capacity curve obtained from these simulations, which varies with temperature, reveals dual peaks near Tc for both cases. The first peak, labeled Peak I, occurs below Tc and is attributed to temperature-induced domain reorientation. The second peak, labeled Peak II, occurs above Tc and arises from stress-induced phase transitions between paraelastic and ferroelastic states. This transition results in a double-loop strain–stress hysteresis, akin to the polarization-field hysteresis observed in ferroelectric systems at and above Tc. Between Peak I and Peak II, there is a dip in damping capacity just below Tc, caused by the diminished ferroelasticity of BaTiO3 particles near this critical temperature. In composite materials, the dual peaks merge into a single peak due to the heterogeneous nature of Tc, influenced by various factors that either raise or lower Tc. This convergence aligns with experimental observations. [ABSTRACT FROM AUTHOR]

The phase separation of protein and RNA mixtures underpins the assembly and regulation of numerous membraneless organelles in cells. The ubiquity of protein–RNA condensates in cellular regulatory processes is in part due to their sensitivity to RNA concentration, which affects their physical properties and stability. Recent experiments with poly-cationic peptide–RNA mixtures have revealed closed-loop phase diagrams featuring lower and upper critical solution temperatures. These diagrams indicate reentrant phase transitions shaped by biomolecular interactions and entropic forces such as solvent and ion reorganization. We employed atomistic simulations to study mixtures with various RNA–polylysine stoichiometries and temperatures to elucidate the microscopic driving forces behind reentrant phase transitions in protein–RNA mixtures. Our findings reveal an intricate interplay between hydration, ion condensation, and specific RNA–polylysine hydrogen bonding, resulting in distinct stoichiometry-dependent phase equilibria governing stabilities and structures of the condensate phase. Our simulations show that reentrant transitions are accompanied by desolvation around the phosphate groups of RNA, with increased contacts between phosphate and lysine side chains. In RNA-rich systems at lower temperatures, RNA molecules can form an extensive pi-stacking and hydrogen bond network, leading to percolation. In protein-rich systems, no such percolation-induced transitions are observed. Furthermore, we assessed the performance of three prominent water force fields—Optimal Point Charge (OPC), TIP4P-2005, and TIP4P-D—in capturing reentrant phase transitions. OPC provided a superior balance of interactions, enabling effective capture of reentrant transitions and accurate characterization of changes in solvent reorganization. This study offers atomistic insights into the nature of reentrant phase transitions using simple model peptide and nucleotide mixtures. We believe that our results are broadly applicable to larger classes of peptide–RNA mixtures exhibiting reentrant phase transitions. [ABSTRACT FROM AUTHOR]

Histogram-reweighting grand canonical Monte Carlo simulations are used to obtain the critical properties of lattice chains composed of solvophilic and solvophobic monomers. The model is a modification of one proposed by Larson et al. [J. Chem. Phys. 83, 2411 (1985)], lowering the "contrast" between beads of different types to prevent aggregation into finite-size micelles that would mask true phase separation between bulk high- and low-density phases. Oligomeric chains of lengths between 5 and 24 beads are studied. Mixed-field finite-size scaling methods are used to obtain the critical properties with typical relative accuracies of better than 10−4 for the critical temperature and 10−3 for the critical volume fraction. Diblock chains are found to have lower critical temperatures and volume fractions relative to the corresponding homopolymers. The addition of solvophilic blocks of increasing length to a fixed-length solvophobic segment results in a decrease of both the critical temperature and the critical volume fraction, with an eventual slow asymptotic approach to the long-chain limiting behavior. Moving a single solvophobic or solvophilic bead along a chain leads to a minimum or maximum in the critical temperature, with no change in the critical volume fraction. Chains of identical length and composition have a significant spread in their critical properties, depending on their precise sequence. The present study has implications for understanding biomolecular phase separation and for developing design rules for synthetic polymers with specific phase separation properties. It also provides data potentially useful for the further development of theoretical models for polymer and surfactant phase behavior. [ABSTRACT FROM AUTHOR]

Phase separation plays a key role in determining the self-assembly of biological and soft-matter systems. In biological systems, liquid–liquid phase separation inside a cell leads to the formation of various macromolecular aggregates. The interaction among these aggregates is soft, i.e., they can significantly overlap at a small energy cost. From a computer simulation point of view, these complex macromolecular aggregates are generally modeled by soft particles. The effective interaction between two particles is defined via the generalized exponential model of index n, with n = 4. Here, using molecular dynamics simulations, we study the phase separation dynamics of a size-symmetric binary mixture of ultrasoft particles. We find that when the mixture is quenched to a temperature below the critical temperature, the two components spontaneously start to separate. Domains of the two components form, and the equal-time order parameter reveals that the domain sizes grow with time in a power-law manner with an exponent of 1/3, which is consistent with the Lifshitz–Slyozov law for conserved systems. Furthermore, the static structure factor shows a power-law decay with an exponent of 4, consistent with the Porod law. [ABSTRACT FROM AUTHOR]

In contrast to the parent compound YCo12B6, the Fe-doped YCo12−xFexB6 (1.5 ≤ x ≤ 2.5) alloys exhibit an antiferromagnetic ground state. It is further revealed that the antiferromagnetic state gets transformed into a forced ferromagnetic state by way of a magnetic-field-induced metamagnetic transition. The results demonstrate a progressive reinforcement of the antiferromagnetic interactions upon increasing Fe content along the YCo12−xFexB6 series of compounds. The magnetic phase diagram of each (x = 1.5, 2, and 2.5) composition is determined by combining isothermal and isofield magnetization measurements. The composition and temperature dependencies of the critical field are derived and discussed. Whereas for x = 2 and 2.5, the magnetic state changes from antiferromagnetic (AFM) to ferromagnetic (FM) and then to the paramagnetic (PM) state upon heating, exhibiting three distinct temperature regions, a multicritical point of magnetic origin is proposed for the x = 1.5 compound at a temperature of about 117 K. The ordering temperature is found to decrease upon increasing Fe concentration, while the critical field of the AFM-FM metamagnetic phase transition shows the opposite trend. The critical transition field diminishes upon increasing temperature. [ABSTRACT FROM AUTHOR]

Many solid crystals exhibit a structural phase transition where a subset of its ions or entire molecules become orientationally ordered. As to why such ordering occurs remains mostly unresolved. We consider the extremely weak magnetic elements arising from the reorientations of the molecules experiencing mutual resonance to play the chief role. Two new features are identified in d-camphor: (1) the magnetic susceptibility abruptly changes when crossing the order–disorder phase transition at TII–III = 239.8 K during cooling and at TIII–II = 245.2 K during warming and (2) the complex dielectric constant exhibits two successive discontinuities only 0.2 K apart near the critical temperatures when the sweeping rate is only 0.1 K/min. We discuss how the change in entropy associated with order–disorder transitions in plastic crystals represents temporal changes rather than spatial changes in the system. Our findings may be extended to study why many other crystalline solids exhibit orientational ordering and irreversibility. [ABSTRACT FROM AUTHOR]

Continued increases in computational power now make it possible to evaluate the free-energy landscape associated with the first-order liquid–liquid transition in realistic models of water for which an accurate estimate of the liquid–liquid critical point exists, and to explore its change with pressure near the coexistence line. We report the results of 50 μs-long NPT umbrella sampling simulations for two realistic models for water, TIP4P/2005 and TIP4P/ice, 3–9 K below their critical temperatures. The free energy profile at different pressures clearly shows the presence of two well-defined free energy basins and makes it possible to identify the liquid–liquid spinodal points, the limits of stability that define the (temperature dependent) pressure range within which two distinct free energy basins exist. The results show that for temperatures less than 10 K below the critical temperature, metastable states are possible across a very limited pressure interval, information that is relevant to the interpretation of experiments probing the metastable phase behavior of deeply supercooled water in the so-called no-man's land. [ABSTRACT FROM AUTHOR]

Boron-based compounds have triggered substantial attention due to their multifunctional properties, incorporating excellent hardness and superconductivity. While tetragonal metal borides LiB4 and NaB4 with BaAl4-type structure and striking clathrate boron motif have been induced under compression, there is still a lack of deep understanding of their potential properties at ambient pressure. We herein conduct a comprehensive study on I4/mmm-structured LiB4 and NaB4 under ambient pressure via first-principles calculations. Remarkably, both LiB4 and NaB4 are found to possess high Vickers hardness of 39 GPa, which is ascribed to the robust boron framework with strong covalency. Furthermore, their high hardness values together with distinguished stability make them highly potential superhard materials. Meanwhile, electron–phonon coupling analysis reveals that both LiB4 and NaB4 are conventional phonon-mediated superconductors, with critical temperatures of 6 and 8 K at 1 atmosphere pressure (atm), respectively, mainly arising from the coupling of B 2p electronic states and the low-frequency phonon modes associated with Li-, Na-, and B-derived vibrations. This work provides valuable insights into the mechanical and superconducting behaviors of metal borides and will boost further studies of emergent borides with multiple functionalities. [ABSTRACT FROM AUTHOR]

Boron-based compounds have triggered substantial attention due to their multifunctional properties, incorporating excellent hardness and superconductivity. While tetragonal metal borides LiB4 and NaB4 with BaAl4-type structure and striking clathrate boron motif have been induced under compression, there is still a lack of deep understanding of their potential properties at ambient pressure. We herein conduct a comprehensive study on I4/mmm-structured LiB4 and NaB4 under ambient pressure via first-principles calculations. Remarkably, both LiB4 and NaB4 are found to possess high Vickers hardness of 39 GPa, which is ascribed to the robust boron framework with strong covalency. Furthermore, their high hardness values together with distinguished stability make them highly potential superhard materials. Meanwhile, electron–phonon coupling analysis reveals that both LiB4 and NaB4 are conventional phonon-mediated superconductors, with critical temperatures of 6 and 8 K at 1 atmosphere pressure (atm), respectively, mainly arising from the coupling of B 2p electronic states and the low-frequency phonon modes associated with Li-, Na-, and B-derived vibrations. This work provides valuable insights into the mechanical and superconducting behaviors of metal borides and will boost further studies of emergent borides with multiple functionalities. [ABSTRACT FROM AUTHOR]

Rare-earth nickelates (RENiO3: RE≠La) exhibit metal–insulator transition (MIT) properties that enable potential applications, such as critical temperature resistance thermistors, optoelectronic switches, and correlated logical devices. Nevertheless, their abrupt structural distortion across MIT results in mechanical stresses and forms microcracks within the bulk RENiO3, and this irreversibly reduces their resistive change during MIT that further impedes their practical applications. Herein, we demonstrate a compositing strategy that simultaneously improves the MIT performances and mechanical strength of RENiO3 by introducing a secondary phase of perovskite oxides with similar lattice parameters and high resistivity. Despite its much higher resistivity compared to RENiO3 (e.g., RE = Sm or Pr), introducing the LaMnO3 compositing phase under high oxygen pressure surprisingly reduces the matrix resistivity. Furthermore, such a compositing process (e.g., 20% LaMnO3) also effectively improves the mechanical strength of RENiO3 by eight times. Such counterintuitive variations are attributed to the similar structure and lattice parameter between RENiO3 and the perovskite composites that modify the grain boundary. As a result, the resistive change is more abrupt across MIT owing to the reduction in the resistivity associated with the grain boundary, while the defect generation and propagation are also suppressed that improves the mechanical properties. This further pave the way to the application of bulk RENiO3 as discrete devices in correlated electronics. [ABSTRACT FROM AUTHOR]

Understanding the condensed-phase behavior of chiral molecules is important in biology as well as in a range of technological applications, such as the manufacture of pharmaceuticals. Here, we use molecular dynamics simulations to study a chiral four-site molecular model that exhibits a second-order symmetry-breaking phase transition from a supercritical racemic liquid into subcritical D-rich and L-rich liquids. We determine the infinite-size critical temperature using the fourth-order Binder cumulant, and we show that the finite-size scaling behavior of the order parameter is compatible with the 3D Ising universality class. We also study the spontaneous D-rich to L-rich transition at a slightly subcritical temperature of T = 0.985Tc, and our findings indicate that the free energy barrier for this transformation increases with system size as N2/3, where N is the number of molecules, consistent with a surface-dominated phenomenon. The critical behavior observed herein suggests a mechanism for chirality selection in which a liquid of chiral molecules spontaneously forms a phase enriched in one of the two enantiomers as the temperature is lowered below the critical point. Furthermore, the increasing free energy barrier with system size indicates that fluctuations between the L-rich and D-rich phases are suppressed as the size of the system increases, trapping it in one of the two enantiomerically enriched phases. Such a process could provide the basis for an alternative explanation for the origin of biological homochirality. We also conjecture the possibility of observing nucleation at subcritical temperatures under the action of a suitable chiral external field. [ABSTRACT FROM AUTHOR]

The line tension of two immiscible liquids under two-dimensional and quasi-two dimensional conditions is calculated as a function of temperature, using mesoscale numerical simulations, finding that it decays linearly. The liquid–liquid correlation length, defined as the thickness of their interface, is also predicted as the temperature is varied, and it diverges as the temperature becomes close to the critical temperature. These results are compared with recent experiments on lipid membranes and good agreement is obtained. The scaling exponents of the line tension (μ) and the spatial correlation length (ν) with temperature are extracted, finding that they fulfill the hyperscaling relationship, μ = d − 1 ν , where d is the dimension. The scaling of specific heat with temperature of the binary mixture is obtained as well. This is the first report of the successful test of the hyperscaling relation between μ and ν for d = 2 and for the non-trivial case of quasi-two dimensions. This work can help to understand experiments that test properties of nanomaterials using simple scaling laws, without needing to know specific chemical details of those materials. [ABSTRACT FROM AUTHOR]

A synthetic methodology was applied to investigate the phase behavior of solution mixtures containing trimethoxyvinylsilane and triethoxyvinylsilane in supercritical carbon dioxide under high-pressure conditions, spanning temperatures up to 393.2 K and pressures up to 20.53 MPa. Critical mixture curves were distinctly observed in both binary systems, exhibiting a maximum within the pressure–temperature domain situated between the critical temperatures of CO2 and the respective constituent. Notably, both systems displayed type-I phase behavior. Solubility curves were generated using the perturbed chain-statistical associating fluid theory (PC-SAFT) equation of state in theoretical analysis. Comparative analysis between the projected and experimental outcomes for the CO2 + trimethoxyvinylsilane and CO2 + triethoxyvinylsilane systems revealed substantial agreement, affirming the efficacy of the PC-SAFT equation of state. [ABSTRACT FROM AUTHOR]

It remains a great challenge to achieve strong and reversible hydrogel adhesion. Hydrogel adhesives also suffer from poor environmental stability due to dehydration. To overcome these problems, here reversible adhesive gels are designed using a new switching mechanism and new solvent. For the first time, the study observes UCST (upper critical solution temperature)‐type thermosensitive behaviors of poly(benzyl acrylate) (PBnA) polymer and gel in menthol:thymol deep eutectic solvents (DESs). The temperature‐induced phase transition allows adjusting cohesive force, and hence adhesion strength of PBnA gels by temperature. To further improve the mechanical and adhesion properties, a peptide crosslinker is used to allow energy dissipation when deforming. The resulting eutectogel exhibits thermal reversible adhesion with a high switching ratio of 14.0. The adhesion strength at attachment state reaches 0.627 MPa, which is much higher than most reversible adhesive hydrogels reported before. The low vapor pressure of DES endows the gel excellent environmental stability. More importantly, the gel can be repeatedly switched between attachment and detachment states. The strong and reversible gel adhesive is successfully used to design soft gripper for the transport of heavy cargos and climbing robot capable of moving on vertical and inverted surface in a manner similar to gecko. [ABSTRACT FROM AUTHOR]

The thermal runaway issue represents a long‐standing obstacle that retards large‐scale applications of lithium metal batteries. Various approaches to inhibit thermal runaway suffer from some intrinsic drawbacks, either being irreversible or delayed thermal protection. Herein, this work has explored thermo‐responsive lower critical solution temperature (LCST) ionic liquid‐based electrolytes, which provides reversible overheating protection for batteries with warning and shut‐down stages, well corresponding to an initial stage of thermal runaway process. The batteries could function stably below 70 °C as a working mode, while demonstrating a warning mode above 80 °C with a noticeable reduction in specific capacitance to delay temperature increase of batteries. In terms of 110 °C as a critically dangerous temperature, a shut‐down mode is designed to minimize the thermal energy releasing as the batteries are barely chargeable and dischargeable. Dynamically growing polymeric particles above LCST contributed to such an intelligent and mild control on specific capacitance. Larger size will occupy larger surfaces of electrodes and close more pores of separators, enabling a gradual suppressing of Li+ transfer and reactions. The present work demonstrated a scientific design of thermoresponsive LCST electrolytes with a superiorly precise and intelligent control of electrochemical performances to achieve self‐adapted overheating protections. [ABSTRACT FROM AUTHOR]

Vanadium dioxide has attracted much interest due to the drastic change of the electrical and optical properties it exhibits during the transition from the semiconductor state to the metallic state, which takes place at a critical temperature of about 68 °C. Much study has been especially devoted to developing advanced fabrication methodologies to improve the performance of VO2 thin films for phase-change applications in optical devices. Films structural and morphological characterisation is normally performed with expensive and time consuming equipment, as x-ray diffractometers, electron microscopes and atomic force microscopes. Here we propose a purely optical approach which combines Polarized Raman Mapping and Phase-Transition by Continuous Wave Optical Excitation (PTCWE) to acquire through two simple measurements structural, morphological and thermal behaviour information on polycrystalline VO2 thin films. The combination of the two techniques allows to reconstruct a complete picture of the properties of the films in a fast and effective manner, and also to unveil an interesting stepped appearance of the hysteresis cycles probably induced by the progressive stabilization of rutile metallic domains embedded in the semiconducting monoclinic matrix. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the post-buckling of sandwich beams possessing functionally graded material (FGM) faces and functionally graded porous (FGP) cores in thermal environment. Thus, the critical buckling temperature and the deformation of such sandwich beams are determined and discussed in detail for three main types of temperature distributions which are uniform, linear and nonlinear temperature rises. An improved third-order shear deformable theory based on more rigorous kinematics of displacements is employed with von Kármán nonlinearity for constructing the energy equations of the problem. A Jacobi–Ritz method cooperating with the direct iteration procedure and Newton–Raphson technique is utilized to carry out the solutions of the sandwich beams associated with several parameters of material composition, porous coefficient, geometrical ratio and others. Based on the results, it can be disclosed that the beams can withstand the deformation due to thermal loadings if they have more pores inside the core. The resistance to deformation brought on by thermal loadings is significantly improved by increasing the sandwich thickness ratio. [ABSTRACT FROM AUTHOR]

Hydrogel‐based actuators are innovative materials that exhibit responsive and dynamic behavior in response to external stimuli, making them promising candidates for a wide range of applications in fields such as soft robotics. We employ 3D printing to create layered rectangles, using a passive ink composed of gelatin methacryloyl (GelMA) and an active ink consisting of GelMA and poly(N‐isopropylacrylamide) (PNIPAM). Our aim is to assess and compare the bending capabilities of these structures based on their layer arrangements in a buffer above the lower critical solution temperature. Therefore, an asymmetric rectangular structure is selected as the shape‐changing component in the tail of a 3D printed fish‐shaped hydrogel actuator. We show that gold nanostars integrated into the actuators serve as photothermal elements, enabling the fish tail to repeatedly bend when near infrared light is turned on and off. Our effort illustrates the potential of combining 3D printing, responsive hydrogels and photothermal elements with near infrared light towards soft robotic applications. This combination yields actuators capable of shape‐shifting without requiring localized light or transitioning between environments with varying temperatures. [ABSTRACT FROM AUTHOR]

We develop a theory of the critical point of the ferromagnetic Ising model, whose basic objects are the ergodic (pure) states of the infinite system. It proves the existence of anomalous critical fluctuations, for dimension ν = 2 and, under a standard assumption, for ν = 3 , for the model with nearest-neighbor interaction, in a way which is consistent with the probabilistic approach of Cassandro, Jona-Lasinio, and several others, reviewed in Jona-Lasinio's article in Phys. Rep. 352,439 (2001). We propose to single out the state at the critical temperature T c , among the ergodic thermal states associated to temperatures 0 ≤ T ≤ T c , by a condition of non-summable clustering of the connected two-point function. The analogous condition on the connected (2r)- point functions, for r ≥ 2 , together with a scaling hypothesis, natural within our framework, proves that the (macroscopic) fluctuation state is quasi-free, after a proper rescaling, also at the critical temperature, in agreement with a theorem by Cassandro and Jona-Lasinio, whose proof is, however, shown to be incomplete. Other subjects treated include topics relating to universality, including spontaneous breaking of continuous symmetries and violations of universality in problems of energetic and dynamic stability. [ABSTRACT FROM AUTHOR]

Light-rare-earth-based RAlSi family serves as an exceptional platform for elucidating the unique properties of Weyl systems, featuring both types of Weyl fermions, with and without magnetism. In this investigation, we conducted a comparative analysis of the resistivity and magnetoresistance (MR) behaviors of single-crystal RAlSi (R = La, Ce, and Pr). A hump appears in the temperature-dependent resistivity curve of CeAlSi, attributed to the crystal-electric-field effect and showing insensitivity to the magnetic field. In nonmagnetic LaAlSi, a quasilinear MR response above the crossover field is linked to mobility fluctuations originating from slight inhomogeneity. Upon heating CeAlSi from 2 K to its critical temperature for ferromagnetic (FM) ordering (TC), a field-induced contraction in the twin Fermi surfaces was observed, likely contributing to negative MR peaks at TC. The robustness of Weyl nodes in FM RAlSi is demonstrated by the inherent broken space inversion symmetry, allowing them to change positions via violation of time-reversal symmetry. Our findings suggest the potential for magnetic modulation of the electronic structure in FM RAlSi, leading not only to shifts in Weyl nodes but also alterations in the Fermi surface. [ABSTRACT FROM AUTHOR]

A hydrogel consisted of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAAm-co-AA) and Prussian blue (PB) was synthesized for a cargo carrier by controlling the release of organic dye under near infrared (NIR) light. The AA moiety of the hydrogel provided chemical bonding with Fe (III) ions for further PB formation. Biocompatible, NIR-responsive PB generated heat and the heat was transferred to the hydrogel. The NIPAAm moiety in the hydrogel was shrunken because of the low critical solution temperature behavior of the hydrogel, and the hydrogel released the loaded dye with 62%. These results suggest dye-loaded hydrogel as a prospective platform for light-triggered carriers. [ABSTRACT FROM AUTHOR]

The physicochemical properties of Y-123 superconducting foams of various topologies prepared by the top-seeded infiltration-growth (TSIG) method are discussed. During the TSIG process, precursor foams (polyurethanes with various densities, flexibilities, and skeleton types) were infiltrated with a green phase (Y-211) and thermally converted to Y-123 superconductors using NdBCO single-crystal seeds oriented in the [100] direction. The occurrence of the desired superconducting phases were confirmed by X-ray diffraction, Raman and X-ray absorption spectroscopies as well as magnetometric and transport measurements. It was found that the growth of Y-123 foam preserves the crystallographic orientation of the NdBCO seed regardless of the initial alignment of the skeleton. The foams exhibit the critical temperature (T c) similar to YBCO bulk. High-density and stiffness skeletons favor the Y-123 phase formation, while more flexible foam structures hamper transformation of the Y-211 phase into the Y-123 one. [ABSTRACT FROM AUTHOR]

The application of portable aluminum‐air batteries (AABs) in extreme environments is an inevitable demand for future development. Aqueous electrolyte freezing is a major challenge for low‐temperature operations. Conventionally, enlightened by the organic system in metal ion batteries, blindly increasing the concentration is regarded as an efficient technique to reduce the freezing point (FP). However, the underlying contradiction between the adjusting mechanism of the FP and OH− transportation is ignored. Herein, the aqueous alkali solution of CsOH is researched as a prototype to disclose the intrinsic conductive behavior and related solvent structure evolution. Different from these inorganic electrolyte systems, the concept of a critical anti‐freezing concentration (CFC) is proposed based on a specific temperature. The relationship between hydrogen bond reconstruction and de‐solvation behavior is analyzed. A high conductivity is obtained at −30 °C, which is also a recorded value in an intrinsic aqueous AAB. The homogenous dissolution of the Al anode is also observed. As a general rule, the CFC concept is also applied in both the KOH and NaOH systems. [ABSTRACT FROM AUTHOR]

The group of moiré graphene superconductors keeps growing, and by now it contains twisted graphene multilayers as well as untwisted stacks. We analyze here the contribution of long-range charge fluctuations in the superconductivity of twisted double bilayers and helical trilayers, and compare the results to twisted bilayer graphene. A diagrammatic approach which depends on a few, well-known parameters is used. We find that the critical temperature and the order parameter differ significantly between twisted double bilayers and helical trilayers on one hand, and twisted bilayer graphene on the other. This trend, consistent with experiments, can be associated with the role played by moiré Umklapp processes in the different systems. [ABSTRACT FROM AUTHOR]

The geometrical properties of a helical ferromagnet are shown theoretically to control the critical temperature of a proximity-coupled superconductor. Using the Usadel equation for diffusive spin transport, we provide self-consistent analysis of how curvature and torsion modulate the proximity effect. When the helix is attached to a piezoelectric actuator, the pitch of the helix—and hence the superconducting transition—can be controlled electrically. [ABSTRACT FROM AUTHOR]

This study examines the superconducting properties of titanium nitride (TiN) deposited via plasma-enhanced atomic layer deposition on both planar and three-dimensional (3D) structures. Our deposition method achieves consistent uniformity, maintaining sheet resistance ( R □ ) > 95% across a 6-in. wafer, crucial for large-scale superconducting device fabrication and yield optimization. The planar films, akin to reactive-sputtered TiN, reached a critical temperature (Tc) of 4.35 K at a thickness of ≈ 40 nm. For aspect ratios (ARs) between 2 and 40, we observed a single transition of ≈ 2 K at ARs between 2 and 10.5, and multiple transitions at ARs > 10.5. We discuss mechanisms influencing superconducting properties in the 3D structures, aligning with current and future superconducting technologies. [ABSTRACT FROM AUTHOR]

Common wall lizards (Podarcis muralis) in Italy show a striking variation in body coloration across the landscape, with highly exaggerated black and green colors in hot and dry climates and brown and white colors in cool and wet climates. Males are more intensely colored than females, and previous work has suggested that the maintenance of variation in coloration across the landscape reflects climatic effects on the strength of male–male competition, and through this sexual selection. However climatic effects on the intensity of male–male competition would need to be exceptionally strong to fully explain the geographic patterns of color variation. Thus, additional processes may contribute to the maintenance of color variation. Here we test the hypothesis that selection for green and black ornamentation in the context of male–male competition is opposed by selection against ornamentation because the genes involved in the regulation of coloration have pleiotropic effects on thermal physiology, such that ornamentation is selected against in cool climates. Field observations revealed no association between body coloration and microhabitat use or field active body temperatures. Consistent with these field data, lizards at the extreme ends of the phenotypic distribution for body coloration did not show any differences in critical minimum temperature, preferred body temperature, temperature‐dependent metabolic rate, or evaporative water loss when tested in the laboratory. Combined, these results provide no evidence that genes that underlie sexual ornamentation are selected against in cool climate because of pleiotropic effects on thermal biology. [ABSTRACT FROM AUTHOR]

This study investigates the enhancement of superconducting properties in Cu0.5Tl0.5Ba2Ca2Cu3O10-δ superconductor via inclusion of Cu nano-particles (Cu NPs) and high-pressure pelletization. The (Cu)x/CuTl-1223 nano-particles superconductor composites were synthesized by solid-state reaction technique and pelletized using a cold isostatic press (CIP). X-ray diffraction analysis confirmed the retention of tetragonal crystal structure and dominant CuTl-1223 phases in the nanocomposites. SEM images showed a decrease in the density of void/pores as well as an improvement in weak-link connections. FTIR spectra indicated no significant changes in the vibrational oxygen modes, confirming that the crystal structure remained intact. Resistivity (ρ ) measurements unveiled a remarkable boost in the critical temperature T c (0) to 110 K and activation energy (Uo) to 0.028 eV at the optimal 1.5 wt.% of copper (Cu) nano-particle concentrations, and decreasing beyond these concentrations at 0.4 GPa. This enhancement of superconducting parameters is attributed to improved weak-link connectivity, reduced porosity, and increased superconducting volume fraction, leading to higher carrier charge concentrations in the (Cu)x/CuTl-1223 nanocomposites. [ABSTRACT FROM AUTHOR]

Critical review of temperature criteria for controlling cracking due to concrete hardening Various limits for the concrete temperature are specified for the production of concrete on site. These are primarily to ensure the workability of the fresh concrete in extreme weather conditions and to ensure proper hydration. There are also additional concrete temperature requirements for certain applications to reduce the risk of cracking or crack intensity due to hardening‐induced restraint stresses. In this context, the maximum member temperature, the maximum fresh concrete temperature or the maximum temperature gradient across the cross‐section are generally limited. However, these limits are defined independently of the ambient temperature. The extent to which these temperature limits are justified in terms of the risk of cracking due to concrete hardening is investigated using thermo‐mechanical simulations on 3D volume models. In detail, the temperature and stress evolution due to concrete hardening is simulated for different member types and ambient boundary conditions and evaluated with respect to the associated risk of cracking. The systematic evaluation of the results shows that the general limits of maximum member temperature and fresh concrete temperature are only pragmatic solutions for controlling the risk of cracking due to concrete hardening. These limits should always be considered with regard to the ambient temperature. [ABSTRACT FROM AUTHOR]

Body temperature is critical indicator of human health, and its real‐time monitoring is crucial for assessing body status and disease diagnosis. In this work, a flexible temperature sensor is presented that employs a graphite/polyvinylidene fluoride (PVDF)/polyaniline composite and demonstrates a negative temperature coefficient (NTC). This sensor exhibits high sensitivity (−0.832%/ °C), rapid response time (11.05 s), and excellent linearity (R2 = 0.98). Its integration with a self‐adhesion PDMS‐PEG substrate layer ensures close skin contact, enhancing the accuracy of temperature measurements. Notably, the sensor's stability and resistance to sweat and deformation ensure continuous, reliable temperature monitoring, even during extensive exercise. This sensor thus represents a significant advancement in flexible and waterproof temperature sensing technologies. [ABSTRACT FROM AUTHOR]

Ecological networks comprising of mutualistic interactions can suddenly transition to undesirable states, such as collapse, due to small changes in environmental conditions such as a rise in local environmental temperature. However, little is known about the capacity of such interaction networks to adapt to a rise in temperature and the occurrence of critical transitions.Here, combining quantitative genetics and mutualistic dynamics in an eco‐evolutionary framework, we evaluated the stability and resilience of mutualistic networks to critical transitions as environmental temperature increases. Specifically, we modelled the dynamics of an optimum trait that determined the tolerance of species to local environmental temperature as well as to species interaction. We then evaluated the impact of individual trait variation and evolutionary dynamics on the stability of feasible equilibria, the occurrence of threshold temperatures at which community collapses, and the abruptness of such community collapses.We found that mutualistic network architecture, that is the size of the community and the arrangement of species interactions, interacted with evolutionary dynamics to impact the onset of network collapses. Some networks had more capacity to track the rise in temperatures than others and thereby increased the threshold temperature at which the networks collapsed.However, such a result was modulated by the amount of heritable trait variation species exhibited, with high trait variation in the mean optimum phenotypic trait increasing the environmental temperature at which networks collapsed. Furthermore, trait variation not only increased the onset of temperatures at which networks collapsed but also increased the local stability of feasible equilibria.Our study argued that mutualistic network architecture interacts with species evolutionary dynamics and increases the capacity of networks to adapt to changes in temperature and thereby delayed the occurrence of community collapses. [ABSTRACT FROM AUTHOR]

Structurally well‐defined small molecules with lower critical solution temperature (LCST) behavior offer enormous prospects for fine‐tuning their phase transition properties to be "on‐demand" applied in the specific scene but are still underexplored. Herein, a novel amphiphilic small LCST molecule is rationally designed and synthesized. The molecule, namely TG, features a conjugation of multiple short ethylene glycol (EG) chains with the functional coordinating terpyridine (Tpy) moiety. The molecule TG demonstrates excellent LCST behavior down to 0.05 × 10−3m in a water solution. And a cloud point Tcp = 30.9 °C with a very short thermal hysteresis ΔT = 0.2 °C and good reversibility can be achieved when c = 0.1 × 10−3m. The excellent LCST properties of TG have enabled its successful performance as the smart window for solar radiation management with the ∆Tlum, ∆TIR, and ∆Tsol being 83.6%, 49.1%, and 67.2%, respectively. Moreover, the presence of Tpy moiety in TG enables its coordination with Ru3+ and the resulting complex also exhibits modulated LCST behavior with different concentration‐dependent Tcp. These studies would provide novel small‐molecule‐based scaffolds for constructing better solar radiation management systems as well as other thermal‐responsive smart materials. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO2) undergoes a reversible first‐order metal‐to‐insulator transition (MIT) from a high‐temperature metallic phase to a low‐temperature insulating phase at a critical temperature Tc of 68°C. The MIT is accompanied by a structural phase transition. In addition to the metallic high‐temperature rutile phase, several insulating phases may be involved depending on doping, interfacial stress, or external stimuli. Unambiguously identifying the crystal phases involved in the phase transition is of key interest from the point of view of application as well as fundamental science. We study the impact of Ti doping of VO2 thin films on (110) rutile TiO2 substrates. We conduct a careful analysis of structural properties by combining results of x‐ray diffraction, Raman spectroscopy, and transmission electron microscopy. The transition temperature Tc of the deposited thin films decreases with increasing Ti‐content. All our thin film samples undergo a structural phase transition from the monoclinic M1‐phase to the rutile R‐phase with increasing temperature without passing the intermediate monoclinic M2‐phase. A careful analysis of polarization and angle‐dependent Raman data reveals that, above Tc, the unit cell of the high‐temperature rutile TixV1‐xO2 phase is aligned with that of the rutile TiO2 substrate whereas, below Tc, 180°‐domains of the M1‐phase of TixV1‐xO2 are observed. The structural relationship between TiO2 substrate and the high respective low‐temperature phase of the TixV1‐xO2 determined by Raman spectroscopy is in excellent agreement with TEM results on these samples. Raman spectroscopy is a powerful tool for studying structural changes of VO2‐based samples in the vicinity of MIT. [ABSTRACT FROM AUTHOR]

In this paper, we propose integrating factor (IF)‐based methods for solving the Cahn–Hilliard (CH) equation, which was originally proposed to describe the phase separation phenomenon for binary melted alloy below the critical temperature, and since then, it has appeared in many fields. Being a nonlinear equation, it is of great importance to develop efficient numerical methods for investigating the solution behavior of the CH equation. We present a few important linear and nonlinear schemes for the CH equation and obtain error estimates for those schemes. The integrators that we present here are of first and second order in time. We show numerical results to illustrate our theoretical findings. [ABSTRACT FROM AUTHOR]

The equilibrium behaviors of the anisotropic XY ferromagnet, with nonmagnetic impurity, have been investigated in three dimensions by Monte Carlo simulation using Metropolis algorithm. Two different types of anisotropy, namely, the bilinear exchange type and single-site anisotropy are considered here. The thermodynamic behaviors of the components of the magnetizations (M), susceptibility (χ) and the specific heat (C) have been studied systematically through extensive Monte Carlo simulations. The ferro–para phase transition has been observed to take place at a lower temperature for impure anisotropic XY ferromagnet. The pseudocritical temperature ( T c ∗ ) has been found to decrease as the system gets more and more impure (impurity concentration p increases). In the case of bilinear exchange type of anisotropy (λ), the pseudocritical temperature ( T c ∗ ) increases linearly with λ for any given concentration of nonmagnetic impurity (p). The slope of this linear function has been found to depend on the impurity concentration (p). The slope decreases linearly with the impurity concentration (p). In the case of the single-site anisotropy (D), the pseudocritical temperature ( T c ∗ ) has been found to decrease linearly with p for fixed D. The critical temperature (for a fixed set of parameter values) has been estimated from the temperature variation of fourth-order Binder cumulants ( U L ) for different system sizes (L). The critical magnetization (M (T c)) and the maximum value of the susceptibility ( χ p ) are calculated for different system sizes (L). The critical exponents for the assumed scaling laws, M (T c) ∼ L − β ν and χ p ∼ L γ ν , are estimated through the finite size analysis. We have estimated, β ν , equals 0. 4 8 ± 0. 0 5 and 0. 3 7 ± 0. 0 4 for bilinear exchange and single-site anisotropy, respectively. We have also estimated, γ ν equals 1. 7 8 ± 0. 0 5 and 1. 8 1 ± 0. 0 5 for bilinear exchange and single-site anisotropy, respectively. [ABSTRACT FROM AUTHOR]

The adverse impact of vehicle emissions on the roadside environment is becoming increasingly serious. Traditional catalytic materials exhibit a singular practical effect and are prone to aggregation within asphalt systems. This study employed organic montmorillonite (MMT) as a two-dimensional nanomaterial load-bearing phase for graphitic carbon nitride (g-C3N4) based on the structural features of available materials and the concept of composite material construction, resulting in the synthesis of a g-C3N4/MMT composite material (CN-M). The phase composition, binding behavior, thermal stability, physical adsorption capacity, and morphology of CN-M were studied systematically. The results demonstrate that CN-M possesses stable properties and structural morphology. The specific surface area of CN-M is 3.38 times that of g-C3N4 , indicating superior spatial confinement capabilities. A comprehensive analysis was conducted from both macroscopic and microscopic perspectives on the modification mechanism, rheological characteristics, aging behavior, and catalytic performance of the modified asphalt. It is speculated that CN-M disperses in a layered state within the asphalt binder, effectively restricting the movement of asphalt macromolecular chains. When the CN-M content reached 5%, the modified asphalt exhibited a high-temperature critical temperature of 71.6°C, showcasing optimal high-temperature rheological performance and aging resistance. The prepared modified asphalt mixture demonstrated the ability for waste degradation, achieving a degradation rate of 21.66% for nitric oxide (NO). The research results provide technical support for the development and application of catalytic asphalt materials. [ABSTRACT FROM AUTHOR]

This paper addresses the combustion of ammonium perchlorate (AP) near adiabatic conditions at high pressures and higher initial temperatures. The AP pellets were coated with a thin layer of silica grease to simulate the near adiabatic condition. The experiments were performed at initial temperatures of 30 and 70 °C in the pressure range of 2.5–30 MPa for coated and bare pellets. The bare pellets were found to exhibit mesa burning as reported in the literature. However, the coated pellets did not exhibit mesa burning. The burn rates of coated AP pellets increased linearly for the entire pressure range of 2.5–30 MPa with 0.64 pressure index. Further, the experiments were carried out for the first time at an initial temperature of 90 °C for 14–30 MPa pressure range, wherein, AP combustion did not display any characteristics of mesa burning (pressure index of 0.33). The surface morphology of quenched samples of both bare and coated pellets of AP were studied, by quenching (rapid depressurization technique) pellets at 6, 12, and 18 MPa pressures. The surface structure of quenched samples for near adiabatic conditions was similar for all three pressures. However, for bare pellets the changes in surface structure were observed with change in pressure, similar to the literature. Mesa burning was found to be an effect of convective heat loss from the periphery of the pellets and it was not observed when heat loss was reduced or initial temperature was higher than the critical initial temperature. [ABSTRACT FROM AUTHOR]

This research investigates the synergistic impact of Trinidad Lake Asphalt (TLA) and Crumb Rubber Modifier (CRM) on the performance characteristics of PG 64-22 asphalt binder. Employing Superpave test analysis and Multiple Stress Creep Recovery (MSCR) testing, our study reveals that the incorporation of TLA significantly elevates the viscosity of the binder due to its high asphaltene content. This viscosity enhancement translates to increased stiffness and durability of the asphalt binder. Furthermore, CRM contributes to improved elasticity and deformation resistance, counterbalancing the stiffness induced by TLA. Our results indicate that the combined use of TLA and CRM not only boosts viscosity but also mitigates stiffness, thereby enhancing the binder's resistance to rutting, especially post-aging. However, an elevated concentration of TLA increases the risk of fatigue cracking, a concern effectively alleviated through the integration of CRM. At a critical temperature of −12 °C, Bending Beam Rheometer (BBR) tests demonstrate that TLA augments stiffness while CRM enhances low-temperature flexibility. This study underscores the necessity of optimizing TLA and CRM ratios to achieve a balance between enhanced performance and practical feasibility. The findings highlight the potential of TLA and CRM to substantially improve asphalt binder performance, contributing to the longevity and resilience of pavement structures. [ABSTRACT FROM AUTHOR]

The performance of the perturbed‐chain statistical associating fluid theory‐type equations of state (PC‐SAFT‐type EOSs) is compromised in predicting properties of pure compounds in the critical region. In our previous research, we introduced an improved volume‐translated rescaled PC‐SAFT EOS (VTR‐PC‐SAFT EOS) by incorporating a dimensionless distance‐function. Such VTR‐PC‐SAFT EOS is built based on a critical point‐based PC‐SAFT EOS that can reproduce the critical temperature, critical pressure, and critical molar volume of pure compounds. VTR‐PC‐SAFT EOS is found to significantly improve the accuracy of phase behavior predictions in both critical and noncritical regions for pure compounds. In this study, we assess the performance of VTR‐PC‐SAFT EOS in reproducing the critical and noncritical properties of 251 pure compounds, encompassing 20 distinct chemical species. The testing results indicate that, compared to the other three PC‐SAFT‐type EOSs, the VTR‐PC‐SAFT EOS can consistently provide more accurate representations of critical and noncritical properties of 251 pure compounds. [ABSTRACT FROM AUTHOR]

The joint of longitudinally connected slab track is vulnerable to damage from environmental impacts and repeated train loads. Under high temperature environments, the joint becomes a high risk area for track slab upwarp, which significantly affects the upwarp stability of the track slab and the safe operation of trains. This study employs the arc length approach and a finite element model to investigate the upwarp equilibrium development path of the track slab, the upwarp evolution process of the track slab under the joint damage is further analyzed. Then, the influence of different initial defects on the vertical stability of the track slab is studied. Utilizing dimensional analysis, a general formula for calculating the critical temperature rise of the track slab is proposed. The results are as follows: (1) The entire upwarp process of track slab under joint damage can be divided into three stages: stability, upwarping development, and instability. (2) A nonlinear correlation exists between the upwarp critical temperature rise of the track slab and three types of initial defects. Height defects in narrow joints exert the most significant impact on the critical temperature rise, followed by initial Out-of-straight (initial OOS), with the initial bending shape having the least effect. The complete defect of the narrow joint reduces the upwarp critical temperature rise of the track slab by 53.26°C, a 48.4% reduction. (3) A unified expression, derived from the characteristic parameters of initial defects and dimensional analysis, can more accurately predict the upwarp critical temperature rise of the track slab. [ABSTRACT FROM AUTHOR]

Herein, a series of ternary hydride compounds MXH12$\left(\text{MXH}\right)_{12}$ crystallizing in the cubic Pm3¯m$P m \bar{3} m$ structure as potential rare‐earth and alkaline‐earth superconductors are designed and investigated. First‐principles calculations are performed on these prospective superconductors across the pressure range of 50–200 GPa, revealing their electronic band structures, phonon dispersions, electron–phonon (e–ph$p h$) interactions, and superconducting properties. Several compounds are identified as dynamically stable, with ScYbH12$_{12}$ and LuYbH12$_{12}$ remaining stable at 70 GPa and ScLuH12$\left(\text{ScLuH}\right)_{12}$ at 100 GPa. Notably, Eliashberg theory and e–ph$p h$ coupling calculations predict CaLuH12$_{12}$ to exhibit a remarkable Tc$T_{\text{c}}$ of up to 294 K at 180 GPa. In these findings, ternary hydrides are unveiled as a promising class of high‐temperature superconductors and insights are provided for achieving superconductivity at lower or ambient pressures through material design and exploration. [ABSTRACT FROM AUTHOR]

The mechanisms behind the polymer glass transition, though not fully elucidated, have garnered significant attention. The Locally Correlated Lattice (LCL) theory [R. P. White, J. E. Lipson, Macromolecules2016, 49, 3987] provides a novel perspective on free volume and establishes the relationship between polymer glass transition and free volume. In this study, we present a dynamic theoretical model based on the thermodynamic LCL theory, focusing on the kinetic evolution of free volume during polymer glass transition. Our analysis simultaneously examines the segmental diffusion coefficient, dynamic correlation length, free volume, and isobaric heat capacity. The results indicate that, upon reaching a critical temperature, heterogeneous dynamics and singular thermodynamics emerge concurrently. This study establishes a comprehensive correlation between thermodynamic singularities and dynamic inhomogeneities, offering valuable insights into the polymer glass transition process. [ABSTRACT FROM AUTHOR]

Understanding the origin of superconductivity in correlated two-dimensional materials is a key step in leveraging material engineering techniques for next-generation nanoscale devices. While it is widely accepted that phonons fluctuations only mediate conventional (s-wave) superconductivity, the common phenomenology of superconductivity in Bernal bilayer and rhombohedral trilayer graphene, as well as in a large family of graphene-based moiré systems, suggests a common superconducting mechanism across these platforms. In particular, in all these platforms some superconducting regions violate the Pauli limit, indicating unconventional superconductivity, naively ruling out conventional phonon-mediated pairing as the underlying mechanism. Here we combine first principles simulations with effective low-energy theories to investigate the superconducting mechanism and pairing symmetry in rhombohedral stacked graphene multilayers. We find that phonon-mediated superconductivity explains the main experimental findings, namely the displacement field and doping level dependence of the critical temperature, and the presence of two superconducting regions with different pairing symmetries that depend on the parent normal state. In particular, we find that intra-valley phonon scattering favors a triplet f-wave pairing when combined with electronic correlations stabilizing a spin- and valley-polarized normal state. We also propose a so far unexplored superconducting region at higher hole doping densities nh ≈ 4 × 1012 cm−2, and demonstrate how this highly hole-doped regime can be reached in heterostructures consisting of monolayer α-RuCl3 and rhombohedral trilayer graphene. Our findings promote phonon-mediated pairing as a strong contender to explain superconductivity across a wide range of graphene platforms, and demonstrate that phonons can, in fact, stabilize unconventional superconducting orders. [ABSTRACT FROM AUTHOR]

Introduction: Olive cultivation, like other evergreen fruit cropsworldwide, is limited by the occurrence of frost episodes in different times of the year, mainly in winter or early spring. Some contradictory results are reported about cultivars' response to frost, which depends on the physiological stage of the tissues (acclimated or not acclimated) when the cold or frost episode occurs. This work aimed to implement a user-friendly and reliable lab method for discerning frost tolerance. Methods: Our methodology considered both detached leaves and potted plantlets. The optimal temperature at which damage differentiated between cultivars was evaluated, as well as the time of exposure to cold and the recovery time for the correct evaluation of the symptoms. Furthermore, a comparative analysis of damage on both young and mature leaves was conducted. To validate the efficacy of the methodology, assessments were conducted on the cultivars 'Arbequina' (tolerant), 'Picual' (moderately tolerant), and 'Frantoio' (susceptible) under acclimated and non-acclimated conditions. Results and discussion: The results indicated that, when detached leaves were used for frost evaluation, a temperature of -10°C ± 1°C for 30 min and a recovery time at 26°C for 24-48 h after exposure to cold are enough to induce damages on the leaves and discriminate between cultivar susceptibility. Under these conditions, a precise assessment of symptoms can be made, facilitating the categorization of frost tolerance level in various olive cultivars. Notably, no significant differences were observed between young and mature leaves during the evaluation process. On the other hand, the critical temperature to assess damages on potted plantlets was determined to be -7°C ± 1°C. In addition, it was observed that acclimated plants exhibited fewer symptoms compared to non-acclimated ones, with 'Frantoio' being the most affected alongside 'Picual' and 'Arbequina'. Conclusion: The implemented methodology will allow the assessment of frost tolerance in several olive cultivars within a short timeframe, and it is proven to be user-friendly and reliable. [ABSTRACT FROM AUTHOR]

Coal spontaneous combustion often occurs in hidden areas and is one of the main disasters in mines. The process of coal spontaneous combustion can be effectively blocked by adding inhibitors. A composite phase change material with stable performance and large heat storage was prepared based on the staged characteristics of coal oxidation and the critical temperature point. To further explore the inhibitory properties of the material, three factors were selected: inhibitor concentration, coal samples particle size and coal samples volatilization, and the orthogonal table were used to design the experiment. The variation law of index gas with coal temperature was obtained through the programmed heating device. Compared with the characteristic temperature values of CO occurrence temperature, fire coefficient R2 = 0.02 and R3 = 0.1, the range and variance analysis showed that when the addition amount was 4%, the material had the best performance in inhibiting coal oxidation. Then, the effectiveness of range analysis was verified according to the response surface method. According to the infrared spectroscopy experiment, it is found that the composite phase change material effectively reduced the content of oxygen-containing functional groups and methylene groups, and slowed down the process of coal oxidation and self-heating. In addition, during the oxidation process of coal, the material decomposes water molecules to increase the hydroxyl content, which was conducive to reducing the coal temperature. [ABSTRACT FROM AUTHOR]

The ability of thermoresponsive polymers to respond to temperature with a reversible conformational change makes them promising 'smart' materials for solutions in medical and biotechnological applications. In this work, two such polymers and structural isomers were studied: poly(N-isopropyl acrylamide) (PNiPAm) and poly(2-isopropyl-2-oxazoline) (PiPOx). We compare the critical solution temperatures (CST) of these polymers in D2O and H2O in the presence of Hofmeister series salts, as results obtained under these different solvent conditions are often compared. D2O has a higher dipole moment and electronegativity than H2O, which could significantly alter the CST transition. We used two complementary methods to measure the CST, dynamic light scattering (DLS) and differential scanning calorimetry (DSC) and found that the CST decreased significantly in D2O compared to H2O. In the presence of highly concentrated kosmotropes, the CST of both polymers decreased in both solvents. The influence of the kosmotropic anions was smaller than the water isotope effect at low ionic strengths but considerably higher at physiological ionic strengths. However, the Hofmeister anion effect was quantitatively different in H2O than in D2O, with the largest relative differences observed for Cl−, where the CSTs in D2O decreased more than in H2O measured by DLS but less by DSC. PiPOx was more sensitive than PNiPAm to the presence of chaotropes. It exhibited much higher transition enthalpies and multistep transitions, especially in aqueous solutions. Our results highlight that measurements of thermoresponsive polymer properties in D2O cannot be compared directly or quantitatively to application conditions or even measurements performed in H2O. [ABSTRACT FROM AUTHOR]

In order to improve the inhibition effect of gel on coal spontaneous combustion, a chitosan (CS)/polyacrylamide (PAM)/metal ion (Al3+) composite double-network gel was developed in this study. The optimum formula of the composite double-network gel was determined using orthogonal experimentation. The microstructure, water retention, compressibility, and anti-destruction properties of the composite double-network gel were analyzed. The inhibition effect of the composite double-network gel on coal spontaneous combustion was studied via infrared spectroscopy and a synchronous thermal analyzer from the micro and macro perspectives. The results show that the composite double-network gel has a denser interpenetrating double-network structure and a larger void ratio than the ordinary gel. The water retention rate was 55% after standing at 150 °C for 12 h. The deformation memory ratio of the composite double-network gel was 78%, which was 26.8% higher than that of the ordinary gel, and the compressive strength also increased by 59.96%. In addition, the critical temperature point and the maximum thermal weight-loss rate temperature point decreased by 7.01 °C and 39.62 °C, respectively, and the composite double-network gel effectively reduced active functional groups in the treated coal sample, such as hydroxyl and aliphatic hydrocarbons. In this study, a CS/PAM/Al3+ composite double-network gel was produced, which exhibited good gel performance and inhibition effects, with physical effects such as the covering, wetting, and cementation of coal. [ABSTRACT FROM AUTHOR]

The development of temperature-sensitive sensors upgraded by poly(N-isopropylacrylamide) (PNIPAM) represents a significant stride in enhancing performance and tailoring thermoresponsiveness. In this study, an array of temperature-responsive electrochemical sensors modified with different PNIPAM-based copolymer films were fabricated via a "coating and grafting" two-step film-forming technique on screen-printed platinum electrodes (SPPEs). Chemical composition, grafting density, equilibrium swelling, surface wettability, surface morphology, amperometric response, cyclic voltammograms, and other properties were evaluated for the modified SPPEs, successively. The modified SPPEs exhibited significant changes in their properties depending on the preparation concentrations, but all the resulting sensors showed excellent stability and repeatability. The modified sensors demonstrated favorable sensitivity to hydrogen peroxide and L-ascorbic acid. Furthermore, notable temperature-induced variations in electrical signals were observed as the electrodes were subjected to temperature fluctuations above and below the lower critical solution temperature (LCST). The ability to reversibly respond to temperature variations, coupled with the tunability of PNIPAM's thermoresponsive properties, opens up new possibilities for the design of sensors that can adapt to changing environments and optimize their performance accordingly. [ABSTRACT FROM AUTHOR]

Characterizing the optimal operating parameters for a heat pump with a specific refrigerant is paramount, as it provides valuable guidance for refrigerant selection. The temperature mismatch between cold and hot fluids in the evaporator and condenser can lead to degraded thermal performance in heat pumps with large temperature variations. To address these two key issues, we selected several pure refrigerants with varying critical temperature levels for use in a large temperature variation heat pump configuration. The corresponding thermal performance was then investigated using the Ebsilon code under fixed temperature lift conditions as the operating temperature varied. It indicates that the maximum coefficient of performance (COP) is typically achieved when the deviation factors of temperature and pressure from their critical parameters fall within the ranges of 0.62~0.71 and 0.36~0.5, respectively. Our research recommends the binary refrigerant mixture of R152a/R1336mzz(z) (COP = 3.54) for the current operating conditions, as it significantly improves thermal performance compared to pure R1336mzz (z) (COP = 2.87) and R152a (COP = 3.01). Through research on the impact of the compositional ratio of R152a/R1336mzz(z) on the thermal performance of the heat pump, we found that that the optimal ratio of R1336mzz(z) component to R152a component is 0.5/0.5. This study offers valuable guidance for selecting the most suitable refrigerants for heat pumps in practical engineering design scenarios. [ABSTRACT FROM AUTHOR]