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In the NiTi-Hf alloy system, coherent H-phase (orthorhombic) nanoprecipitates have been shown to have strong impact on the B2 (cubic) to B19' (monoclinic) martensitic transformation (MT) and the corresponding stress-strain behavior. Two typical martensite-precipitate microstructures have been observed: intra-martensite precipitates (IMP) and inter-precipitate martensites (IPM). In the former, high density small H-phase nanoprecipitates are embedded in individual domains of different variants of the B19' martensite that form a herringbone structure, while in the latter, finer twinning B19' martensites are confined in between larger H-phase nanoprecipitates. In this study we investigate the mechanisms underlying the formation of these two distinct microstructures through computer simulations using the phase field method. In particular, we study temperature- and stress-induced MTs in the presence of H-phase nanoprecipitates, concentration variations and stress field in the B2 matrix created by the precipitation reaction, and the corresponding thermal and stress hystereses and superelasticity for different alloy compositions and aging treatments. The simulation results indicate that densely populated nanoprecipitates 7∼20 nm in length and 3∼8 nm in width lack the strength to impede the growth, coalescence and coarsening of martensitic domains, resulting in the formation of IMP. In contrast, plate-like nanoprecipitates with diameters of ∼100 nm and thickness of ∼20 nm effectively hinder the growth, coalescence and coarsening of martensitic domains, giving rise to IPM. The IPM microstructure is accompanied by an almost linear volume fraction vs. temperature curve with less than 1 °C hysteresis during thermal cycling and a slim stress-strain hysteresis as compared to that of the IMP microstructure. Therefore, thoughtful choices in alloy composition and aging treatment enable the attainment of distinctly varied precipitate and martensitic microstructures, each characterized by unique pseudoelastic or superelastic properties. [Display omitted] [ABSTRACT FROM AUTHOR]

The demand for advanced shape memory alloys, with good processability, high stability, and excellent superelasticity, is highly desirable in widespread practical applications. Here, we demonstrated a novel Fe-34Mn-12.5Al-7.5Ni-2.5Ta-0.05B (at%) polycrystalline alloy (FMAN-Ta-B) with good strain-recovery pseudoelastic behavior (5.68% at a compressive strain of 8%), ultra-low thermal hysteresis (∼81 K), and relatively high stability. In this alloy, highly ordered D0 3 -structured precipitates (Ta-riched Fe 3 Al) (∼26.3 nm) coupled with B2 precipitates (NiAl) (∼19.6 nm), and dispersive distributed in the A2 (austenitic) matrix. On the one hand, D0 3 -structured precipitates act as a connecting structure between B2 precipitates and the matrix, exhibiting low mismatch with the matrix and inducing a thermoelastic martensitic transformation and good strain recovery in the alloy. On the other hand, D0 3 nanoprecipitates with high structural and thermal stability limited the growth of B2 precipitates and reduced the size-dependence of the superelasticity for the B2 precipitate, thus elevating the aging temperature and enhancing the thermostability of superelasticity. The drastically improved superelasticity and low thermal hysteresis provide useful insights into the design of high-performance ferrous superelastic alloys. [Display omitted] • A novel FeMnAlNiTaB superelastic alloy with relatively high stability was designed. • A thermoelastic martensitic transformation was induced in that alloy. • The role of D0 3 and B2 phase in the improvement of superelasticity was elucidated. • D0 3 precipitate limited the growth of B2 precipitate, enhancing the thermo-stability. [ABSTRACT FROM AUTHOR]

The martensitic transformation in NiTi-based Shape Memory Alloys (SMAs) provides a basis for shape memory effect and superelasticity, thereby enabling applications requiring solid-state actuation and large recoverable shape changes upon mechanical load cycling. In order to tailor the transformation to a particular application, the compositional dependence of properties in NiTi-based SMAs, such as martensitic transformation temperatures and hysteresis, has been exploited. However, the compositional design space is large and complex, and experimental studies are expensive. In this work, we develop an interpretable piecewise linear regression model that predicts the λ 2 parameter, a measure of compatibility between austenite and martensite phases, and an (indirect) factor that is well-correlated with martensitic transformation hysteresis, based on the chemical features derived from the alloy composition. The model is capable of predicting, for the first time, the type of martensitic transformation for a given alloy chemistry. The proposed model is validated by experimental data from the literature as well as in-house measurements. The results show that the model can effectively distinguish between B 19 and B 19 ′ regions for any given composition in NiTi-based SMAs and accurately estimate the λ 2 parameter. • Developed an interpretable model for phase compatibility in shape memory alloys from alloy composition. • Investigated key compositional features influencing phase compatibility. • Compiled lattice parameters and thermodynamic targets from literature, enhanced by 8 novel in-house experimental data points. [ABSTRACT FROM AUTHOR]

• An accurate measurement method for the third-order elastic constants is proposed. • Stepwise coda wave interferometry provides a high resolution in velocity change. • The relative wave velocity changes are highly sensitive to the thermal effect. • The estimation error of thermo-acoustoelastic constants is within 3.54%. Accurate determination of third-order elastic constants (TOECs) is important for quantifying the nonlinear elastic responses of solid materials. However, conventional experiments are laborious and may produce data with large error margins, so the TOECs of many isotropic materials have not been obtained. To solve this problem, a reliable and accurate measurement method based on the thermo-acoustoelastic effect was developed to determine the TOECs of isotropic materials. Additionally, the relationships between the thermo-acoustoelastic constant (TAEC) of bulk waves and TOECs under different constraints were derived. Subsequently, the thermal effect was employed as the driving force for bulk wave velocity change, and a simple thermal cycling experimental procedure was constructed to investigate the thermo-acoustoelastic responses of 6061-T6 aluminum. The experimental results indicated that bulk wave velocity changes caused by thermal strain were 19.4 times greater than in conventional acoustoelastic experiments. This heightened sensitivity could significantly reduce experimental measurement errors. Furthermore, the linear regression slope of thermal hysteresis curves was used to calculate TAEC, demonstrating excellent repeatability and reproducibility. Notably, the TAEC estimation error was within 3.54%, which is nearly unattainable with conventional methods. Finally, the effectiveness of the proposed method was verified by comparing TOECs obtained from thermal cycling experiments and acoustoelastic experiments. This study provides new insights into thermo-acoustoelastic behavior and will promote the development of nonlinear ultrasonic testing techniques. [Display omitted] [ABSTRACT FROM AUTHOR]

• A Brayton refrigeration cycle with novel MnFe-based composite material is proposed. • Experimental and theoretical researches are fully integrated. • Effects of thermal hysteresis on the cycle performance are discussed. • The main thermodynamic quantities of the refrigeration cycle are calculated. • Thermodynamic quantities with composite and constituent materials are compared. MnFeP(As, Ge, Si) series compounds are three kinds of MnFe-based magnetocaloric materials, which have giant magnetocaloric effect. In this work, the experimental characteristic curves of new style Mn-Fe-P-Si materials, numbered as 1: Mn 1.32 Fe 0.67 P 0.52 Si 0.49 , 2: Mn 1.37 Fe 0.63 P 0.5 Si 0.5 , and 3: Mn 1.35 Fe 0.66 P 0.5 Si 0.5 are presented. Based on the experimental data of these component materials and thermodynamic analysis method, a novel composite material is put forward. The optimal molar mass ratios of the composite material are obtained and they are 0.22, 0.33, 0.45, respectively. A regenerative Brayton refrigeration cycle employing the optimal composite material with thermal hysteresis as the working medium is built. By numerical calculation, the influences of thermal hysteresis on the main thermodynamic quantities are evaluated. The results show that the thermal hysteresis of the working medium results in a decrease of 13.6%, 14.6%, 18.8%, and 16.1% of the cooling quantity, net cooling quantity, optimally working temperature range, and coefficient of performance, respectively. These conclusions are beneficial to the optimal parameter design and performance improvement of active magnetic refrigerators. [ABSTRACT FROM AUTHOR]

Extreme cold marine and freshwater temperatures (below 4 °C) induce massive deterioration to the cell membranes of organisms resulting in the formation of ice crystals, consequently causing organelle damage or cell death. One of the adaptive mechanisms organisms have evolved to thrive in cold environments is the production of antifreeze proteins with the functional capabilities to withstand frigid temperatures. Antifreeze proteins are extensively identified in different cold-tolerant species and they facilitate the persistence of cold-adapted organisms by decreasing the freezing point of their body fluids. Various structurally diverse types of antifreeze proteins detected possess the ability to modify ice crystal growth by thermal hysteresis and ice recrystallization inhibition. The unique properties of antifreeze proteins have made them a promising resource in industry, biomedicine, food storage and cryobiology. This review collates the findings of the various studies carried out in the past and the recent developments observed in the properties, functional mechanisms, classification, distinct sources and the ever-increasing applications of antifreeze proteins. This review also summarizes the possibilities of the way forward to identify new avenues of research on anti-freeze proteins. [ABSTRACT FROM AUTHOR]

The temperature variant of the first-order reversal curves (TFORC) analysis technique is emerging as a useful tool for the study of the thermal hysteresis in magnetocaloric alloys undergoing first-order phase transitions. This work demonstrates the capabilities of the TFORC technique for reconstructing and deconvoluting the reversible and irreversible components of thermomagnetic transitions through the integration of the TFORC distributions. Through numerical simulations, the influence of applying smoothing protocols, the presence of noise in the magnetization curves or the distance between the hysteretic first-order phase transition and the Curie transitions of the phases have been tested. By employing the appropriate integration protocol of TFORC distributions, the transformed phase fraction can be separated from the total thermomagnetic behavior. The results obtained from the numeric simulations have been confirmed by applying the proposed analysis methods to the experimental TFORC results of a Ni-Mn-In Heusler alloy sample undergoing magnetic first-order phase transition. In this way, the TFORC technique can be stablished as a valuable characterization method for magnetostructural phase transition materials. • TFORC can be used to reconstruct thermomagnetic curves. • All factors affecting the reconstruction process are analyzed. • Phase fraction of thermomagnetic phase transformation can be extracted. • T-dependent structural characterization is not required for this purpose. • Procedures are validated with experimental data of a Heusler alloy. [ABSTRACT FROM AUTHOR]

Negative thermal expansion (NTE) behavior with giant thermal hysteresis exceeding 450 K has been observed in Fe 3 NiB x. This behavior is desirable in the field of pipe joint or encapsulation. The temperature dependent X-ray diffraction and magnetization indicate that NTE behavior with giant thermal hysteresis is related to crystal structure transition between face-centered cubic (fcc) and body-centered cubic (bcc), but not to the magnetic transition. The introduction of boron can reduce the NTE temperature range and stabilize the high temperature fcc phase. Therefore, we can obtain the NTE behavior below room temperature during cooling process, which is important for the practical application. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Single-phase Ba 1-x Sr x TiO 3 (BST) perovskite ceramics with 0.3 ≤ x ≤ 0.4 were prepared from powders synthesized via sol-gel route. The compositions have the ferroelectric-paraelectric phase transition close to room temperature. At 20 °C the BST ceramics are ferroelectric for 0.3 ≤ x ≤ 0.35 and paraelectric for x = 0.375 and x = 0.40. The study follows the relation between the structural changes produced when increasing the Sr content and the dielectric properties at low intensity electric fields. It is found that the grain size and tetragonality decreases as the Sr content increases. Analyses of complex permittivity and impedance spectroscopy reveal the temperature and frequency dependencies of the dielectric properties. The phase transitions seem to be of first order for all compositions, with a thermal hysteresis that decreases with increasing the Sr content, fact attributed to the corresponding increase of the grain boundaries weight allowing a more efficient stress relaxation in the structure during the change of the symmetry from cubic to tetragonal. The diffusiveness degree during the phase transition is increasing with Sr content, suggesting some relaxor-type contribution attributed to smaller grain size. The ac conductivity follows the universal Jonscher law, with an ac component having the power parameter s independent of Sr content, and a dc component that it is thermally activated with an activation energy of about 0.7–0.77 eV attributed to oxygen vacancies acting as donor-like defects. The fit of impedance spectra at different temperatures and frequencies is obtained by using an equivalent circuit accounting the grains, grain boundaries, electrode interfaces and the local contributions produced by reorientation of defect dipoles or defect clusters. All the component circuits have significant variations around phase transitions. These are discussed in relation to structural changes occurring during transition and considering the changes in the distribution of various charges when polarization vanishes. [ABSTRACT FROM AUTHOR]

Understanding the effect of small characteristic length scales on phase transformations requires microscopic observations to identify mechanisms which may influence the progression of the transformation. Here, we report thickness-dependent hysteresis in electrochemically deposited Ni–Mn–Sn Heusler alloy films, as observed by optical microscopy. This approach allows for analyzing size dependent phase transformation behavior within individual grains from films with decreasing thickness. Hysteresis is not correlated with grain size, but increases with decreasing film thickness following a power law relationship. This behavior is attributable to internal friction-induced energy dissipation at the film/substrate interface in microscale alloy films. Image 1 [ABSTRACT FROM AUTHOR]

Antifreeze proteins (AFPs) bind to ice in solutions, resulting in non-colligative freezing point depression; however, their effects on ice nucleation are not well understood. The predominant plasma AFP of winter flounder (Pseudopleuronectes americanus) is AFP6, which is an amphiphilic alpha helix. In this study, AFP6 and modified constructs were produced as fusion proteins in Escherichia coli , subjected to proteolysis when required and purified prior to use. AFP6 and its recombinant fusion precursor generated similar thermal hysteresis and bipyramidal ice crystals, whereas an inactive mutant AFP6 produced hexagonal crystals and no hysteresis. Circular dichroism spectra of the wild-type and mutant AFP6 were consistent with an alpha helix. The effects of these proteins on ice nucleation were investigated alongside non-AFP proteins using a standard droplet freezing assay. In the presence of nucleating AgI, modest reductions in the nucleation temperature occurred with the addition of mutant AFP6, and several non-AFPs, suggesting non-specific inhibition of AgI-induced ice nucleation. In these experiments, both AFP6 and its recombinant precursor resulted in lower nucleation temperatures, consistent with an additional inhibitory effect. Conversely, in the absence of AgI, AFP6 induced ice nucleation, with no other proteins showing this effect. Nucleation by AFP6 was dose-dependent, reaching a maximum at 1.5 mM protein. Nucleation by AFP6 also required an ice-binding site, as the inactive mutant had no effect. Furthermore, the absence of nucleation by the recombinant precursor protein suggested that the fusion moiety was interfering with the formation of a surface capable of nucleating ice. [Display omitted] • Antifreeze proteins and other proteins can inhibit AgI-induced ice nucleation. • A winter flounder antifreeze protein can shift directly from inhibitor to nucleator. • Conversion to an ice nucleator is specific to the antifreeze protein. [ABSTRACT FROM AUTHOR]

In the current work, a Ni–Mn-X (X = Sn, In) type off-stoichiometric, polycrystalline magnetic shape memory alloy (MSMA) having nominal composition Ni 42 Mn 43 Cr 4 Sn 11 (at. %) has been thoroughly investigated in terms of its crystal structure, microstructure, magnetic properties, and magnetocaloric effect (MCE). X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), differential scanning calorimetry (DSC), and magnetic and magneto-transport measurements are used to characterize it. By offering a significant value of parameters related to MCE at the first-order martensite transition (FOMT) and the second-order magnetic transition (SOMT), the "Cr" doping at the "Ni" site enables considerable magnetic refrigeration to occur close to room temperature (RT). The alloy crystallises into coexisting cubic L2 1 austenite and tetragonal L1 0 martensite phases, among which the first one prevails as the leading phase at room temperature (RT) without exhibiting any geometric frustration. Lattice strain is enumerated using the Williamson-Hall method. A huge working temperature spans of 29.65 K and 26.16 K; the maximum magnetic entropy changes of +8.70 J kg−1.K−1 and −5.04 J kg−1.K−1 and the maximum refrigerant capacities (RC) of 284.24 J. Kg−1 and 234.10 J. Kg−1 across FOMT and SOMT, respectively at an applied magnetic field of 6 T are found to be most suitable for real technological applications. This MSMA offers a comparatively low cost of the constituent elements (Ni, Mn, Cr, and Sn), as well as exhibits giant MCE and RC across both FOMT and SOMT, making it an excellent candidate for magnetic refrigeration near RT. It also opens up new avenues for future research on novel Heusler alloys of this type. • In this work, we have investigated that doping Cr at Ni site provides giant magnetocaloric effect (MCE) near room temperature (RT) in the annealed-quenched Ni 42 Mn 43 Cr 4 Sn 11 magnetic shape memory alloy (MSMA) system. • The observed giant MCE quantified by the maximum magnetic entropy changes of +8.70 J kg−1.K−1 and −5.04 J kg−1.K−1 and refrigerant capacities (RC) of 284.24 J. Kg−1 and 234.10 J. Kg−1 at an applied magnetic field of 6 T across both the first order martensite transition (FOMT) and the second order magnetic transition (SOMT), the high working temperature span of 29.65 K and relatively low cost of the constituent elements make this alloy suitable for magnetic refrigeration as an alternative of conventional gas compression refrigeration. • It also follows a phenomenological model proposed here and hence provides a new future scope of further research on this type of Heusler alloys. [ABSTRACT FROM AUTHOR]

• Aggregation network varied in both degree and type with gelling temperature. • Lower temperatures created a stronger and crumbly gel. • Stronger gels corresponded to a network of greater enthalpy and entropy. • Bonds showed partial thermal irreversibility. Gelation of maltodextrin (DE 2) was examined over a range of temperatures to understand the behaviour within mixed-gel systems. Maltodextrin solutions were prepared at 95 °C and held at temperatures between 5 °C and 60 °C for four days. Bulk gel properties and the underlying microstructure were analysed using fracture strength, proton relaxation time, and differential scanning calorimetry (DSC). Holding at lower temperatures led to a greater gel strength with a brittle and crumbly texture. Analysis of the microstructure showed that gelation at 10 °C versus 60 °C produced a greater number of aggregates (melting enthalpy 14.5 J/g versus 3.4 J/g) and structuring of a higher melting entropy (45 mJ/g K versus 10 mJ/g K). A thermal hysteresis with signs of structure corresponding to both holding temperatures was also measured. Elevated temperature was hypothesized to decrease the amount of smaller molecular weight chains participating in aggregation by shifting from the helix to coil form. [ABSTRACT FROM AUTHOR]

MnMX (M = Co or Ni, X = Si or Ge) alloys with strong magnetostructural coupling exhibit giant magnetic entropy change and are currently extensively studied. However, large thermal hysteresis results in serious irreversibility of the magnetocaloric effect in this well-known system. In this work, we report a low thermal hysteresis and large reversible magnetocaloric effect in a MnNiGe-based system. The introduction of Fe into both Ni and Mn sites can establish stable magnetostructural transitions from paramagnetic hexagonal to ferromagnetic orthorhombic phases. Fascinatingly, a low thermal hysteresis of 5.2 K is achieved in Mn 0.9 Fe 0.2 Ni 0.9 Ge alloy with a large magnetization difference of 62.1 A m2/kg between the two phases. These optimized parameters lead to a partially reversible phase transformation under a magnetic stimulus and bring about a large reversible magnetic entropy change of −18.6 Jkg−1K−1 under the field variation of 0–5 T, which is the largest value reported in MnMX system up to now. Moreover, this low-hysteresis magnetostructural transformation and large reversible magnetocaloric effect can be tuned by doping with Si in a wide temperature range covering room temperature. We also introduce geometrically nonlinear theory to discuss the origin of low hysteresis in MnMX alloys. A strong relation is found between thermal hysteresis and the change of c axis in the orthorhombic structure during the transition. Our work greatly develops the potential of MnMX alloys as magnetocaloric materials and is meaningful to seek or design a MnMX system with low thermal hysteresis. Image 1 [ABSTRACT FROM AUTHOR]

A detailed investigation of the thermal hysteresis, electrical and magnetic properties of La 0.5 Ca 0.5 Mn 1-x Al x O 3 manganites was carried out by resistivity and magnetization measurements. Rietveld refinement of X-ray diffraction patterns indicates an orthorhombic structure with Pnma space group for all samples. The magnetic susceptibility measurements on samples with Al doping up to x = 0.0125 indicated that the charge and orbitally ordered CE-type antiferromagnetic (AFM) state is suppressed and the ferromagnetic (FM) phase increases. With further increase in Al content the FM phase is also suppressed and an A-type AFM insulating state is stabilized. The thermal hysteresis decreases in the samples up to x = 0.0125 whereas it increases by further enhancement of doping up to x = 0.025. The rotation direction of the thermal hysteresis loop changes from counterclockwise to clockwise with increasing of Al doping. Also, the magnetization measurement indicates that saturation magnetization is initially enhanced by increasing doping level up to 0.0125 whilst it is slightly reduced by further increasing doping content. Magnetization versus magnetic field loops of samples at zero field cooled (ZFC) and field cooled (FC) modes at 5 K showed an instable behaviour in the low doping, while in high doping the magnetization curve of ZFC and FC overlapped, demonstrating the stable FM and AFM phases. The results of the resistivity measurements confirmed change in thermal hysteresis and thermal cycling. The thermal hysteresis and cycling behaviour are attributed to the interfacial elastic energy in the boundary between FM and CO–AFM phases. • A first-order transition phase was observed in all samples. • With Al doping up to x = 0.0125 the antiferromagnetic phase is suppressed. • The thermal hysteresis decreased up to x = 0.0125 and increased for x > 0.0125. • The thermal hysteresis loop changed from counterclockwise to clockwise with Al doping. [ABSTRACT FROM AUTHOR]

A thermodynamic theory for the lower-bound hysteresis in martensitic transformations is developed. It is shown that the elastic energy generated by the transformation-induced crystal lattice misfit makes the system free energy a nonlinear function of the volume fractions of the phases, lifts the additivity principle and ergodicity hypothesis of the conventional Gibbsian thermodynamics, and produces a macroscopic energy barrier between the parent and product phases. Since the energy barrier is proportional to the macroscopic volume of the system and thus cannot be surmounted by the thermally assisted nucleation of the new phase, a rate-independent hysteresis of thermodynamic nature is produced, which sets the lower bound for the total transformation hysteresis. This lower-bound hysteresis is characterized by two critical temperatures of the martensitic and reverse transformations, one during cooling and another during heating, with their difference defining the corresponding transformation hysteresis. The necessary undercooling and overheating are intrinsic material properties determined by the transformation elastic energy. The theory is tested against experimental observations, explains the ubiquitous temperature hysteresis in the martensitic transformations, and correlates the hysteresis with the volumetric misfit strain of the transformations. The proposed theory is generic and is applicable to any displacive (diffusionless and martensitic) phase transformations. Image 1 [ABSTRACT FROM AUTHOR]

Highlights • The Mn 1.2 Fe 0.8 P 0.6 Si 0.4 B 0.05 alloys were prepared by ball milling and spinning methods. • The RCE values are 238 and 286 J⋅kg−1 under 0–5 T for bulk and ribbon samples, respectively. • The magnetic hysteresis of ribbon sample decreased by 80% compared with bulk sample. Abstract The Mn 1.2 Fe 0.8 P 0.6 Si 0.4 B 0.05 alloys were prepared by ball milling and melt-spinning methods. The structure and magnetic characteristics of all samples were examined by X-ray diffraction, vibrating sample magnetometer and SEM. Results show that both the ribbon and bulk alloys can crystallize in a hexagonal Fe 2 P-type phase with some impurity phase. The lattice parameters, a and c , of Fe 2 P-type phase are 6.02960 Å, 6.03033 Å, and 3.42310 Å, 3.44431 Å for ribbon and bulk Mn 1.2 Fe 0.8 P 0.6 Si 0.4 B 0.05 alloys, respectively. The Curie temperature increased by 20% from 165 K in bulk to 197 K in ribbon while thermal hysteresis and magnetic hysteresis decreased by 28% and 80% for ribbon sample, respectively. Moreover, the values of magnetic entropy change can be tuned from 15.7 J⋅kg−1⋅K−1 in bulk to 21.8 J⋅kg−1⋅K−1 in ribbon under 0–5 T, resulting in the effective refrigerant capacity (RCE) increasing from 238 to 286 J⋅kg−1. The nature of the phase transitions was studied through the Arrott plots, indicating that the samples undergo first-order ferro-paramagnetic phase transitions. The origin of magnetic hysteresis losses is also discussed deeply. Furthermore, this alloys with large magnetic entropy change could be an interest potential for future magnetic refrigeration applications. [ABSTRACT FROM AUTHOR]

Abstract The correlation between structure and dielectric properties of lead-free (1-x)Na 0.5 Bi 0.5 TiO 3 - xCaTiO 3 ((1-x)NBT - xCT) polycrystalline ceramics was investigated systematically by X-ray diffraction, combined with impedance spectroscopy for dielectric characterizations. The system shows high miscibility in the entire composition range. A morphotropic phase boundary (MPB), at 0.09 ≤ x < 0.15 was identified where rhombohedral and orthorhombic symmetries coexist at room temperature. The fraction of orthorhombic phase increases gradually with x in the MPB region. Dielectric measurements reveal that the relative permittivity increase with addition of Ca2+. This behavior is unusual with this kind of doping. A thermal hysteresis occurred only in the MPB composition which varies in a non-monotonically manner with x, detected by dielectric properties. This phenomenon is related to the crystalline microstructure by a linear relationship between the fraction of each phase and dielectric properties, and, more precisely, to the strong interaction between rhombohedral and orthorhombic phases. [ABSTRACT FROM AUTHOR]

Abstract Stator lining of positive displacement motor (PDM) is prone to generate thermal fatigue failure because of viscoelastic hysteresis of the rubber material. Based on the thermo-mechanical coupling modeling and rubber material testing, finite element method was used to study the effect of environment temperature and thermo-viscoelastic hysteresis to the lining thermal failure of general stator and uniform wall thickness stator. The results show that the deformation and temperature field of general rubber lining has been less affected by the environment temperature than thermo-viscoelastic hysteresis whose distribution of temperature field appears oval-shaped and the temperature gradient is large. Stator lining's temperature increases with the increasing of motor interference and well depth, and the rubber lining's thermal failure modes observed in practice are consistent with the calculation results. The temperature field distribution of uniform wall thickness rubber lining is relatively uniform, and the highest temperature and temperature rise are less affected by the motor interference and well depth, especially with small motor interference and in the shallow well. Therefore, the uniform wall thickness rubber lining has very obvious advantages in prolonging service life and improving the work performance of PDM. Highlights • Maximum deformation of general stator rubber lining occurs at the top of the lining. • Deformation curve of general rubber lining inner wall indicates a sinusoidal periodic changes. • Highest temperature is at the centre of the rubber lining's thickest section. • Thermal failure occurred in the thickest section of the lining, which is consistent with observations in practice. • The temperature field and deformation of uniform wall thickness rubber lining is more uniform. [ABSTRACT FROM AUTHOR]

Hysteresis of martensitic transformations (MTs) is a crucial factor which affects the efficiency and lifetime of actuators and magnetocaloric devices. In the present work we found a tenfold reduction of the thermal hysteresis of MT caused by increasing the MT temperature in a series of Ni(Co)-Mn-Sn thin films deposited onto MgO (001). We have observed that this evolution is accompanied by a drastic change of the temperature dependence of the lattice parameter in the temperature interval of MT. Such a behaviour can be interpreted using the concept of the critical state, where an anhysteretic behaviour is expected. [ABSTRACT FROM AUTHOR]

The redox system of Co 3 O 4 /CoO is very promising for the thermochemical energy storage systems coupled to concentrated solar power plants because of its high energy storage density and reversibility. Nevertheless, the practical application of Co 3 O 4 /CoO system is limited by thermal hysteresis of the redox reaction and material sintering. Here, we synthesized Co-based metal oxides doped with Al and Cr, and studied the influence of the doping of these two metal elements on the thermochemical properties and sintering resistance of the pure Co 3 O 4 /CoO system. Both Al and Cr doping narrows the thermal hysteresis of the Co 3 O 4 /CoO system. In particular, when the molar doping rate of Al is 10%, the thermal hysteresis of Co–Al oxides is only 4.02 °C, which is much narrower than that of pure Co 3 O 4 , and the increase of its oxidation temperature also means that a higher level of thermal energy can be released during oxidation. In the redox cycle, the addition of Al inhibits material sintering and the formation of a loose porous structure facilitates the oxidation, ensuring the reversibility of the redox reaction. The 10% Al–Co honeycomb shows stable conversion behavior with an average conversion of 77.75% in 15 redox cycles. Co–Al oxides exhibit excellent oxidative exothermic characteristics and long-term cycle stability, making them suitable for efficient thermochemical energy-storage processes. • The redox thermal hysteresis of cobalt oxide was modified by doping Al and Cr. • Al-doped oxides show better anti-sintering properties. • High recyclability of cobalt oxide was achieved by doping 10 mol% Al. [ABSTRACT FROM AUTHOR]

• The interfacial thermal resistance shows a switchable, step-like enhancement by varying the number of fullerene, where the magnitude can be enhanced by a factor of two. • The switchable phenomenon can be analyzed using analytic expressions based on the thermal transport theory. • The switchable phenomenon can be realized by applying mechanical strain or by varying the temperature of the sandwich structure. • The temperature range can be increased using mechanical strain, demonstrating the robust environmental sensitivity of the proposed thermal switch structure. [Display omitted] Switchable thermal devices are attracting significant research interest as a basic thermal management component. In this work, taking graphene/fullerene/graphene sandwiches as an example, we demonstrate that the interfacial thermal resistance can show a switchable, step-like change by varying the number of fullerenes in the sandwich structure. Changing the number of fullerenes causes a structural transition between the graphene layers from adhered to separated, resulting in an enhancement of about a factor of two in the interfacial thermal resistance during this on/off switchable phenomenon, which we analyze using analytic expressions based on the thermal transport theory. We further illustrate that the switchable phenomenon can also be realized by applying mechanical strain or by varying the temperature of the sandwich structure. This work demonstrates that the sandwich-liked nanoscale heterostructures can exhibit hysteretic changes in heat transport, and thus have promise for potential applications in switchable thermal devices. [ABSTRACT FROM AUTHOR]

Shape memory alloys, exhibiting shape memory effect and superelasticity, are the key components of actuators and sensors. However, the hysteresis and cyclic instability associated with the martensitic phase transformation, limit their use in the long-duration precise control. We report a quaternary TiNiCuFe shape memory alloy with ultra-low hysteresis and high cyclic stability. The discovery of this alloy is guided by investigating the synergistic effect of Fe and Cu on the martensitic phase transformation. The optimized alloy Ti 50 Ni 45.2 Cu 1 Fe 3.8 , shows a hysteresis measured by electric resistance, as low as 0.3 K (the hysteresis by differential scanning calorimetry is about 3.5 K), and a shift of phase transformation temperature about 0.05 K (after 60 cycles). Compared to the state-of-the-art TiNiCuPd alloy with a Cu content higher than 10 at %, the Cu content in our alloy is reduced to only 1 at %, thereby suppress the brittleness and improve the workability. In addition, the precious metal, Pd is replaced by the low-cost Fe, which may facilitate the wide applications of shape memory alloys. The origin of the optimized hysteresis and cyclic stability, is ascribed to the possible phase coexistence of B19 and R that is realized by manipulating the phase transformation paths with Fe and Cu. This singular microstructure may accommodate more phase transformation strain and consequently mitigate the incompatibility of the austenite/martensite interfaces. [Display omitted] • A Ti 50 Ni 45.2 Cu 1 Fe 3.8 shape memory alloy with a very low hysteresis of 0.3 K is designed. • The alloy shows a shift of phase transformation temperature only about 0.05 K after 60 thermal cycles. • Compared to TiNiCuPd alloy, the Cu content is reduced from 12 at % to 1at % improving the plastic deformation ability. [ABSTRACT FROM AUTHOR]

Thermal hysteresis (TH) is defined as the temperature difference between the melting points and crystallization temperatures of phase-change materials (PCMs). The magnitude of the TH is proportional to the energy loss in a system. In addition, the latent heats of the PCMs cannot be exploited if the TH is beyond the operation temperature range of a system. In this study, Zn/TiO 2 , Zn/Al 2 O 3 , and Zn/SiO 2 core-shell microparticles were synthesized and the TH values of the microparticles were examined. The TH for the microparticles was mainly affected by the ramping rate in differential scanning calorimetry, the shell thermal resistance and the required temperature for heterogeneous nucleation. Given that Al 2 O 3 possesses a superior thermal conductivity than that of TiO 2 and SiO 2 , the Zn/Al 2 O 3 core-shell microparticles provided the smallest TH among the three types of microparticles. The heat capacity of the salt can be enhanced by 6.7% by doping with 10 wt% Zn/Al 2 O 3 microparticles while the viscosity increased from 1.3 to 3 cp. The study provided guidelines to modulate the TH of PCMs, and the concept learned from this study can be applied to enhancing the thermal energy storage in various thermal systems. [ABSTRACT FROM AUTHOR]

Two strategies have been described for cold tolerance in arthropods: (1) freeze-tolerant organisms, which can survive the formation of ice crystals and (2) freeze-avoidant organisms, which prevent the ice crystal formation by super cooling their internal fluids. We studied two arthropods from the Andean Range in central Chile (2400 m a.s.l.), the stick insect Agathemera crassa commonly named as “Chinchemolle” , and the tarantula spider Euathlus condorito commonly named as “Araña pollito”, in order to evaluate how they respond to low temperatures at the physiological and molecular levels. We sampled the soil temperature during one year to track the temperature changes that these organisms must overcome. We found minimum temperatures around −6 °C in autumn, while the temperature were stable at 0 °C in winter due to the snow. The average field-cooling rate was 0.01 ± 0.006 °C min −1 . For both arthropods we determined the super cooling point (SCP) at a cooling rate of 1 °C min −1 and its subsequent survival, finding that A. crassa is a freezing tolerant organism with a SCP of −3.8 ± 1.8 °C and 100% survival, while E. condorito is a freezing avoidant organism with a SCP of −3.0 ± 1.3 °C and 0% survival. The SCP and survival were not affected by the season in which individuals were collected, the SCP was significantly affected by the cooling rate of the experiment. Both species had low molecular weight cryoprotective in their hemolymph that could explain their cold-tolerance behavior. Glucose, glycerol, and trehalose were found in A. crassa's hemolymph, only glucose and glycerol were found in E. condorito's . We analyzed the hemolymph proteins and found no seasonal differences in composition for either species and also we detected protein antifreeze activity in the hemolymph from both arthropods. [ABSTRACT FROM AUTHOR]

Samples of lead–free Ba(Zr x Ti 1-x )O 3 bulk and thick film were fabricated using solid state reaction and tape – casting technique, respectively. A comprehensive investigation of dielectric, ferroelectric, and electrocaloric properties of these samples has been carried out. The results show that there is a dielectric relaxation behavior in the thick film Meantime, the “re–entrant relaxor behavior” and thermal hysteresis are observed in the bulk. Moreover, the electrocaloric effects are observed in the thick film and the bulk. The peak values of Δ T E C of the bulk and the thick film are 2.78 K and 0.37 K, respectively. This work is beneficial for realizing high efficiency and environmentally friendly cooling technology. [ABSTRACT FROM AUTHOR]

A systematic study on the crystal structure and magnetic properties of GdCr 1− x Ru x O 3 (where 0 ≤ x ≤ 0.15) was carried out by powder x-ray diffraction along with low temperature magnetization measurements. Lattice parameters and cell volume continuously increase with doping due to the incorporation and formation of higher ionic radius Ru 4+ and Cr 2+ ion, respectively. Pure GdCrO 3 shows the antiferromagnetic (AFM) ordering at 170 K and a spin-reorientation transition around 8 K. Surprisingly, the AFM ordering temperature does not show any variation with the tetravalent Ru doping; while, spin-reorientation completely disappears with 5% Ru doping within the investigated temperature region. All these compounds exhibit magnetization reversal under low applied fields in field-cooled (FC) protocol. Highly delocalized 4d orbitals and occupation number of Ru 4+ result in a decrease of antisymmetric exchange constant ( D ) with doping. Additionally, the formation of high-spin Cr 2+ in weak octahedral field increases the effective magnetic moment for doped samples. Magnetic relaxation study in FC mode reveals the memory effect of pure GdCrO 3 . Magnetic field-assisted switching behavior study corroborates that magnetic state (positive or, negative) can easily be switched by the application of magnetic field. [ABSTRACT FROM AUTHOR]

Mn 1.15 Fe 0.85 P 0.50 Si 0.45 B 0.05 alloys were prepared by copper mold suction casting method. Subsequent annealing processes were employed to tune the microstructures and magnetocaloric effects. Results show that Mn 1.15 Fe 0.85 P 0.50 Si 0.45 B 0.05 alloys crystallize in a hexagonal phase with the Fe 2 P structure type. With increasing annealing temperature, the lattice parameters of a and c of Fe 2 P-type phase increase from 5.7988(1)Å to 6.0785(2)Å and from 3.3218(1)Å to 3.4727(2)Å for the Mn 1.15 Fe 0.85 P 0.50 Si 0.45 B 0.05 alloys according to XRD. At the same time the Curie temperature and magnetic entropy change increase from 233 K to 244 K and from 8.8 J kg −1 K −1 to 17.0 J kg −1 K −1 (Δ H = 2 T), respectively, while the thermal hysteresis decreases. The entropy changes of these alloys are also estimated from the Clausius-Clapeyron equation, Landau theory and heat capacity, respectively. The nature of the phase transitions were studied through the Arrott plots, which indicate that the samples undergo first-order ferro-paramagnetic phase transitions. However, the universal curve of scaled magnetic entropy change reveals that during the magnetic phase transition, there exists a critical magnetic field, about 1.25 T, below which the sample undergoes a second-order phase transition and above which it displays a first-order phase transition. Furthermore, mechanisms for the large magnetic entropy change and possibilities for the room-temperature magnetic refrigeration are discussed. [ABSTRACT FROM AUTHOR]

Ni - Mn - In - Co Heusler alloys demonstrate promising magnetocaloric performance for use as refrigerants in magnetic cooling systems with the goal of replacing the lower efficiency, eco-adverse fluid-compression technology. The largest change in entropy occurs when the applied magnetic field causes a merged structural and magnetic transformation and the associated entropy changes of the two transformations works constructively. In this study, magnetic and crystalline phase transformations were each treated separately and the effects of the application of magnetic field on thermal hystereses associated with both structural and magnetic transformations of the Ni 52 Mn 25 In 16 Co 7 were studied. From the analysis of synchrotron diffraction data and thermomagnetic measurements, it was revealed that the alloy undergoes both structural (from cubic austenite to a mixture of 7M & 5M modulated martensite) and magnetic (ferromagnetic to a low-magnetization phase) phase transformations. Thermal hysteresis is associated with both transformations, and the variation of the thermal hystereses of the magnetic and structural transformations with applied magnetic field is significantly different. Because of the differences between the hystereses loops of the two transformations, they merge only upon heating under a certain magnetic field. [ABSTRACT FROM AUTHOR]

We investigated the optical behaviors of vanadium dioxide (VO 2 ) films through the semiconductor-to-metal (STM) phase transition using spectroscopic ellipsometry. Correlations between film thickness and refractive index were observed resulting from the absorbing nature of these films. Simultaneously analyzing data at multiple temperatures using Kramers-Kronig consistent oscillator models help identify film thickness. Nontrivial variations in resulting optical constants were observed through STM transition. As temperature increases, a clear increase is observed in near infrared absorption due to Drude losses that accompany the transition from semiconducting to metallic phases. Thin films grown on silicon and sapphire substrate present different optical properties and thermal hysteresis due to lattice stress and compositional differences. [ABSTRACT FROM AUTHOR]

In this work, a series of Mn 5 Ge 3-x Zn x samples were prepared by the arc-melting method. The Rietveld structure refinement of the powder XRD spectrum was performed using the FullProf program. The lattice parameters and cell volume increase with the doping of Zn atoms. From the magnetization curve at 5 K, the compounds show a decreased magnetic moment of the Mn atom with increasing Zn content, resulting from mixing the 3 d electronic state of Mn atoms and the 3 d electronic state of Zn atoms. The small hysteresis loss and soft ferromagnetism of Mn 5 Ge 3-x Zn x indicate that it is suitable for magnetic refrigeration. Thermomagnetic M(T) curves show an increase in thermal hysteresis concurrent with increasing Zn concentration, which is verified by the DSC curve. It is found that the magnetic entropy change and effective magnetic moment decrease with the increase of Zn content, which can be attributable to the doping of Zn atoms resulting in the weakening of the exchange interaction between Mn-Mn atoms and the decrease of magnetic entropy change. In addition, the specific power-law relationships between the magnetic entropy change, the maximum magnetic entropy change, the relative cooling capacity, and the magnetic field of this system were determined, which provides a tool for evaluating the performance of the magnetic refrigerant in the entire magnetic field range. Finally, the specific heat was calculated by the magnetic entropy change obtained by the experiment, and the specific heat curve proves that the sample undergoes a second-order phase transition, consistent with the results of Arrott plots. The T C obtained by the specific heat - Δ C P − T curve is in good agreement with the T C obtained by the magnetic measurement, revealing that T C obtained by the specific heat is also an effective method. • The small hysteresis loss and soft ferromagnetism of Mn 5 Ge 3-x Zn x indicate that it is suitable for magnetic refrigeration. • Thermomagnetic curves and DSC curves verify that the samples has thermal hysteresis. • The magnetic entropy change and effective magnetic moment decrease with the increase of Zn content. • The power-law relationship between the | Δ S M | and H in this system were determined. • The T C obtained by the specific heat curve is also an effective method. [ABSTRACT FROM AUTHOR]

We performed in-situ transmission electron microscope observations on the unconventional ferromagnetic transition in hexagonal (Mn,Fe) 2 (P,Si) magneto-caloric compounds in order to understand the origin of the large thermal hysteresis that is detrimental to magnetic refrigeration. We find that the ferromagnetic transition is coupled to a martensitic-like transformation. Although crystal structure is the same for both paramagnetic (PM) and ferromagnetic (FM) phases, large lattice distortion occurs during the PM-FM transition, which induces energy barrier of about 13.6 kJ/mol. Supercooling or superheating is therefore needed to overcome the energy barrier, which causes the thermal hysteresis for the ferromagnetic transition. [ABSTRACT FROM AUTHOR]

Thermochemical energy storage (TCS) based on gas-solid reactions constitutes a promising concept to exploit reaction enthalpies for thermal energy storage. This concept facilitates the development of efficient storage solutions with higher energy densities compared to widely investigated sensible and latent thermal energy storage systems. Multivalent metal oxides are capable of undergoing a reversible redox reaction at high temperatures, which is why those storage materials are considered particularly suitable for the operating temperature range of concentrated solar power plants with central receiver systems to increase the total plant efficiency and ensure dispatchability of electricity. In the scope of this work a granular manganese-iron oxide with a Fe/Mn molar ratio of 1:3 has been selected as a potentially suitable storage material, which is non-toxic, abundant and economical. For this reason a preparation route from technical grade raw materials has been chosen. The reversible redox reaction is investigated with respect to the thermodynamic and kinetic characteristics by means of simultaneous thermal analysis in dynamic and isothermal series of measurements. Those revealed that the observed presence of a strong divergence of the reactive temperature range from the actual thermodynamic equilibrium can mainly be attributed to kinetic limitations. Expressions for the effective reaction rates are deduced from experimental data for the reduction and oxidation step, describing the dependence of the reaction rate on temperature and oxygen partial pressure, respectively. The expressions are valid for the temperature ranges in proximity to the equilibrium, which are relevant for the targeted operating conditions of the storage reactor in air. The storage material provides good cycling stability in terms of reversibility and widely maintained reactivity throughout 100 redox cycles in air. Future work comprises material modifications, which are expected to further enhance the mechanical stability of the particles. Overall, the manganese-iron oxide of the chosen composition exhibits a redox reactivity practical for regenerator-type storage systems combining a high temperature TCS zone and a lower temperature non-reactive zone merely used for sensible thermal energy storage. [ABSTRACT FROM AUTHOR]

Spruce can grow at an extra low temperature (LT), and is inferred with important antifreezing gene resources. The research here identified 4 different spruce varieties, named as PicW1 , PicW2 , PicM and PicK . Sequence alignment showed base-substitution and deficiency mutations among them with sequence identity between 97.61% and 99.25%. Each gene was transferred into E. coli , where protein was induced by IPTG (isopropyl-β- d -thiogalactoside). Strains cultured at −5 °C showed the lethal dose 50% (LD-50) between 53 h and 57 h for the transgenic strains, but 35 h for the control. Strains cultivated at −20 °C showed the LD-50 between 38 h and 44 h for the transgenic strains, but 25 h for the control. Further, the soluble gene proteins were extracted and purified for Differential Scanning Calorimeter (DSC) test, which showed characteristic thermal hysteresis (TH) value of 0.77 °C (PicW1), 0.78 °C (PicW2), 0.72 °C (PicM), and 0.86 °C (PicK) respectively, significantly higher than the value of 0.05 °C of the control (BSA). Summarily, four homologous proteins showed good antifreeze property with the range from high to low as PicK > PicW2 > PicW1 > PicM. It suggested that they can be used as resources for genetic engineering of plant cold tolerance. [ABSTRACT FROM AUTHOR]

Single phase Mn 0.66 Fe 1.29 P 1- x Si x (0 ≤ x ≤ 0.42) compounds were synthesized using the melt-spinning (rapid solidification) technique. All the compounds form in the Fe 2 P-type hexagonal structure, except a Co 2 P-type orthorhombic structure of the Si-free Mn 0.66 Fe 1.29 P compound. The compounds with 0.24 ≤ x ≤ 0.42 present a FM-PM phase transition, while the compounds with lower Si content show an AFM-PM phase transition. In the Mn 0.66 Fe 1.29 P 1- x Si x compounds, T C and Δ T hys are not only Si content dependent, but also magnetic field dependent. By increasing the Si content from x = 0.24 to 0.42, T C increases from 195 to 451 K and Δ T hys is strongly reduced from ∼61 to ∼1 K. T C increases and Δ T hys decreases with increasing magnetic field, Δ T C /Δ B is about 4.4 K/T. Mn 0.66 Fe 1.29 P 1- x Si x compounds show large saturation magnetic moments with values up to 4.57 μ B /f.u.. A large MCE with a small thermal hysteresis is obtained simultaneously in Fe-rich Mn 0.66 Fe 1.29 P 1- x Si x melt-spun ribbons. [ABSTRACT FROM AUTHOR]

The present study reports systematic rheological data of binary aqueous mixtures of gelatin and alginate up to a concentration ratio of 1:1. The mixtures were prepared and rheologically studied with respect to the gelation point, melting point, and kinetics. The effect of the polysaccharide concentration on the sol–gel and gel–sol transitions is presented for concentrations up to 5% (w/w). Under small amplitude oscillatory shearing conditions, both transitions were shifted to higher temperatures. The kinetic study showed that the storage modulus will continue to increase in time under isothermal conditions, even if the rate of increase is considerably reduced. Furthermore, all binary gels exhibited a higher storage modulus than the pure gelatin gels at 5 °C. The increase was 9 and 24% for 5 and 2.5% gelatin, respectively. Assuming that the storage modulus is directly related to the amount of the triple helixes, all isothermal data could be successfully described by the kinetic gelation model proposed by Djabourov, Leblond, & Papon (1988a, 1988b). The excellent agreement between the rheological data and the gelation model confirm that this model can effectively predict the long-term elastic properties of the binary mixtures. Using isolated prototype modules, discrete gel specimens were formulated at 5 °C. Large amplitude oscillatory shear measurements (LAOS) showed that these specimens were still intact after the tests. The gels that were prepared directly on the rheometer plate exhibited strain hardening behavior during LAOS deformations. A nonlinear stress analysis of the Lissajous plots confirmed this finding. [ABSTRACT FROM AUTHOR]

• A novel antifreeze peptide (AFP) was obtained from silver carp muscle hydrolysate. • The novel AFP (Sc-AFP) was derived from the parvalbumin. • Sc-AFP could bind to 48 water molecules and ice surface via hydrogen bonds. • An FNHK loop of Sc-AFP was a specific binding site for inhibiting ice growth. This study aimed to screen and characterize antifreeze peptides from silver carp muscle hydrolysate (SCMH). The SCMH was initially fractionated by ultrafiltration, and the resultant SCMH-IV (<10 kDa) showing 90 % of yeast survival rate was subsequently separated into four fractions using ion-exchange chromatography. The fraction with the best antifreeze activity was further analyzed by liquid chromatography-tandem mass spectrometry. A total of 514 peptides were identified, of which a novel antifreeze peptide (Sc-AFP, KAADSFNHKAFFAKVG) with a thermal hysteresis activity of 0.87 ℃ was selected. The parvalbumin-derived Sc-AFP showed an alanine-rich, α-helical and amphipathic character. Based on molecular dynamics simulations, the Sc-AFP could interact with 48 water molecules via hydrogen bonds, and could be adsorbed onto the ice surface through a total of 21 hydrogen bonds mainly linked to the lysine residues. This could account for its antifreeze properties via preventing the formation and growth of ice crystals. [ABSTRACT FROM AUTHOR]

Nanoindentation was used to analyze the effect of localized plastic deformation on the martensitic transformation of epitaxial Ni-Mn-Ga films on MgO(001) substrate. Atomic and magnetic force microscopy imaging at elevated temperature was applied to study the martensitic transformation route from the nanometer to the micrometer scale. We analyzed the cooling and heating curves for the martensitic transformation of the nanoindented areas as a function of the applied loads as well as the distance from the material pile-ups around the residual impressions. We observe a thermodynamically governed local increase of the martensitic transformation temperature (i.e. martensite stabilization) as a function of the applied loads. The local increase of the transformation temperature vs. the applied load (P) follows a non-linear regime: reducing the slope by increasing the applied load and showing a plateau for P ≥ 5 mN. The observed effect is local and almost disappears for distances larger than 500 nm from the pile-ups around the residual impressions, where the material transforms similar to the pristine sample. The local increase of transformation temperature as a function of nanoindentation loads is the dominant effect and occurs in both the cooling and the heating curves. Therefore, no considerable thermal hysteresis variation is observed in the transformation of the material. Moreover, we report in average ∼12% higher relative areal shift of the transformation curves over cooling than heating close to the indents reflecting an unequal impact of indents on T M and T A in Ni-Mn-Ga. [Display omitted] [ABSTRACT FROM AUTHOR]

The relationship between the crystallographic compatibility of austenite and martensite phases and the transformation thermal hysteresis (ΔT) of Ni-rich Ni 50.3 Ti 29.7 Hf 20 and Ni 50.3 Ti 29.7 Zr 20 alloys undergoing B2–B19′ martensitic transformation was studied as a function of microstructure, via differential scanning calorimetry, transmission electron microscopy, and X-ray diffraction. An experimental linear relationship of ΔT vs λ 2 (the second eigenvalue of the transformation stretch matrix) was observed for these NiTi(Hf/Zr) alloys, but with a shallower slope as compared to the universal behavior followed by alloys showing B2–B19 martensitic phase transformation. Several ternary NiTiCu and binary NiTi alloys undergoing the B2–B19′ transformation were also found to deviate from the universal behavior attributed to alloys that undergo a B2–B19 transformation, and instead, follow the trend revealed for the present alloy systems. Aged NiTi(Hf/Zr) samples, which consist of very fine nano-precipitates, followed the newly established ΔT vs λ 2 linear relationship, due to only minor changes in the microstructure. In contrast, samples with large precipitates, exhibited a large deviation from this relationship due to much more drastic changes in microstructure. Finally, despite the poor crystallographic compatibility of the austenite and martensite lattices observed in the present alloys, rationalized by large deviation of λ 2 values from 1, relatively low ΔT values were measured. This behavior is actually consistent with the newly established relationship for ΔT vs λ 2 for B2–B19′ transforming alloys, which is much less sensitive to compatibility (shallower slope). It is concluded that such a difference in the ΔT vs λ 2 slope must be a consequence of the crystallography of monoclinic martensite formation in NiTi-based alloys as long as other factors such as plasticity or major constraints to the martensitic transformation do not intervene. [ABSTRACT FROM AUTHOR]

This paper reports the production of micro porous ceramics consisting of TiO 2 and ZrO 2 by direct foaming. ZrO 2 particles in a colloidal suspension were partially hydrophobized using propyl gallate as an amphiphile at a suitable pH range of around 3.5–4.5. A TiO 2 suspension with different mole ratios was added to the surface modified ZrO 2 suspension to obtain ZrTiO 4 -TiO 2 porous ceramics in the sintered sample. The influence of the TiO 2 content and calcination temperature on the phase transformation, microstructure, and thermal properties of the materials was determined by thermal analysis, X-ray diffraction, field emission scanning electron microscopy, and dilatometry. The crystallization of ZrTiO 4 (orthorhombic) was observed at 1100 °C on the thermal hysteresis curve due to anisotropic thermal expansion. The compressive load and displacement of the sintered porous ceramics samples were calculated using the Hertzian indentation method. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) panel temperature was evaluated by developing theoretical models that are feasible to be used in realistic scenarios. Effects of solar irradiance, wind speed and ambient temperature on the PV panel temperature were studied. The parametric study shows significant influence of solar irradiance and wind speed on the PV panel temperature. With an increase of ambient temperature, the temperature rise of solar cells is reduced. The characteristics of panel temperature in realistic scenarios were analyzed. In steady weather conditions, the thermal response time of a solar cell with a Si thickness of 100–500 μm is around 50–250 s. While in realistic scenarios, the panel temperature variation in a day is different from that in steady weather conditions due to the effect of thermal hysteresis. The heating effect on the photovoltaic efficiency was assessed based on real-time temperature measurement of solar cells in realistic weather conditions. For solar cells with a temperature coefficient in the range of −0.21%∼−0.50%, the current field tests indicated an approximate efficiency loss between 2.9% and 9.0%. [ABSTRACT FROM AUTHOR]

In this paper we report on the integration of micro-rods of the [Fe(Htrz) 2 (trz)](BF 4 ) spin crossover compound into an electronic switch-type device. The device has been fabricated by organizing the micrometric particles between interdigitated gold electrodes using dielectrophoresis and the influence of dielectrophoresis parameters on their integration is also examined. A particular attention was devoted to the investigation of the stability of the spin transition and the associated device properties. The stability of the particles before dielectrophoresis was investigated using variable temperature diffuse reflectivity experiments, which revealed a remarkable stability of the spin crossover even after performing 3000 switching cycles. We show also that the spin transition is not influenced by the solvents used for device fabrication, neither by the atmosphere (ambient air or vacuum) in which the device is used. The spin transition remains reproducible over several tens of cycles even at the device level, but the current in the device decreases continuously. [ABSTRACT FROM AUTHOR]

Antifreeze proteins (AFPs) are the key biomolecules that protect species from extreme climatic conditions. Studies of AFPs, which are based on recognition of ice plane and structural motifs, have provided vital information that point towards the mechanism responsible for executing antifreeze activity. Importantly, the use of experimental techniques has revealed key information for AFPs, but the exact microscopic details are still not well understood, which limits the application and design of novel antifreeze agents. The present review focuses on the importance of computational tools for investigating (i) molecular properties, (ii) structure–function relationships, and (iii) AFP-ice interactions at atomistic levels. In this context, important details pertaining to the methodological approaches used in molecular dynamics studies of AFPs are also discussed. It is hoped that the information presented herein is helpful for enriching our knowledge of antifreeze properties, which can potentially pave the way for the successful design of novel antifreeze biomolecular agents. [ABSTRACT FROM AUTHOR]

In this work, the Casimir suspensions of a nanoplate (gold or Teflon) in a liquid environment are theoretically investigated. The substrate of the system is a three-layer structure of Teflon/vanadium dioxide(VO 2)/Teflon. It is found that stable suspensions of nanoplates can be achieved due to the balances of repulsive Casimir forces, gravity and buoyancy. Remarkably, the suspension positions of gold and Teflon nanoplates are strongly associated with the preceding thermal history of VO 2 , i.e., heating or cooling. The differences in the suspension positions between the heating and cooling can reach tens of nanometers. Finally, a thermal hysteresis of Casimir suspensions via the temperature is shown for gold and Teflon nanoplates. Our findings offer the possibility of designing conceptually new devices in micro and nanoelectromechanical systems (MEMS and NEMS). • The Casimir suspensions of gold and Teflon nano-plates are investigated theoretically in a system containing VO 2. • A strong thermal hysteresis of Casimir suspensions is revealed for both gold and Teflon nano-plates. • The suspension positions depend not only on the temperature but also on the preceding thermal history of VO 2. • The discrepancies of the equilibrium positions between the heating and cooling can reach about tens of nanometers. [ABSTRACT FROM AUTHOR]

• Joule heating phenomenon is incorporated in the AC Josephson effect. • The phase and temperature dynamic states are discussed for various parameters. • Device state diagrams are realized for Josephson weak-link – shunted and unshunted. • A useful thermal model as a guide for the experiments with weak-link-based devices. Superconducting weak-link (WL), behaving like a Josephson junction (JJ), is fundamental to many superconducting devices such as nanoSQUIDs, single-photon detectors, and bolometers. The interplay between unique nonlinear dynamics and inevitable Joule heating in a JJ leads to new characteristics. Here, we report a time-dependent model incorporating thermal effect in the AC Josephson regime for a Josephson WL shunted by a resistor together with an inductor to investigate the dynamics as well as the resulting current-voltage characteristics. We find that the dynamic regime where phase and temperature oscillate simply widens due to a pure resistive shunt. However, a significant inductive time-scale in the shunt loop, competing with the thermal time-scale, introduces high-frequency relaxation oscillations in the dynamic regime. Based on numerical analysis, we present state diagrams for different parameter regimes. Our model is a guide for better controlling the parameters in the experiments of WL-based devices. [ABSTRACT FROM AUTHOR]

Spin state bistability within high spin (HS) and low spin (LS) state is investigated in undoped and (Zn, Mn) doped spin crossover (SCO) complex Fe(phen) 2 (NCS) 2 thin films (thickness ∼ 300 nm) deposited by dip-coating technique at room temperature on the quartz substrate. The X-ray diffraction studies clearly show the formation of crystalline structure of SCO complexes. The growth of the thin films was indisputably confirmed by electron microscopy and optical studies. The optical absorption peak between 535-557 nm was clearly observed, and that corresponds to 1A 1g → 1T 1g ligand field absorption in undoped and metal-doped (Zn, Mn) SCO thin films. The high spin (HS) state of the SCO films at room temperature was confirmed by Raman spectra. The bistability of spin states is clearly revealed by the well pronounced thermal hysteresis loop in magnetization measurements. The spin transition temperature (T 1/2) and loop width are found to be critically dependent on metal doping and suggested the possibility of tuning these parameters in spin-crossover thin films to design future spin-based devices. • The thin films of doped and undoped spin-crossover materials Fe(phen) 2 (NCS) 2 , Fe 1−x Zn x (phen) 2 (NCS) 2 , and Fe 1−x Mn x (phen) 2 (NCS) 2 [x = 0,15 and 30%] are deposited on quartz substrates with using a dip-coater, which is developed in our laboratory. • The lattice parameters increased for Mn doped sample while for Zn doped sample the lattice parameters are found to decrease in comparison to the undoped sample. • The spin transition temperature (T 1/2) and loop width are found to be critically dependent on metal doping. • Details of spin-state switching under metal doping of SCO materials are reported here which may be crucial in designing future spin-based devices. [ABSTRACT FROM AUTHOR]

R 2 Cu 2 O 5 (R = Tb-Lu, Sc, In) (RCO) compounds are interesting magnetic materials due to their quasi-low dimensional crystal structure, which also lacks centro-symmetry. Previous investigations on these compounds indicated antiferromagnetic or canted-antiferromagnetic ground state with Néel temperatures lying below about 30 K. The present work tries to provide finer details of the intricate magnetic characteristics of the RCO compounds, which were not addressed in the previous works. These include thermomagnetic irreversibility, thermal hysteresis, hysteresis in the isothermal magnetization measurements and so on. Most interestingly, we observe large magnetocaloric effect as calculated from our magnetization data and we find that it is primarily connected to the metamagnetic transitions observed in the samples. Our work also recognizes anomalies in the dielectric constant at the magnetic transition temperatures indicating possible multiferroicity in the samples. Efforts have been made to understand the diverse magnetic properties of the RCO samples on the basis of the crystal structure and the rare-earth moment. • A comprehensive magnetic scenario of complete R 2 Cu 2 O 5 series in a single report. • Observation of sizable magnetocaloric effect in R 2 Cu 2 O 5 associated with metamagnetism. • Dielectric anomaly at magnetic transition indicates the magneto-electric coupling. • Studies of thermo-magnetic irreversibility, thermal hysteresis in R 2 Cu 2 O 5 oxides. [ABSTRACT FROM AUTHOR]

[Display omitted] Shape memory alloys (SMAs) are desirable candidates for elastocaloric effect materials, but they all suffer from large thermal hysteresis (T hys). This study analyzes multicomponent TiNi-based SMAs dataset by machine learning (ML) to explore new SMAs with narrow T hys. The second-largest eigenvalue λ 2 of the stretch transformation matrix U is added to the original dataset to guide the ML process as a feature. Firstly, λ 2 is obtained by first-principles calculations combined with ML. XGBoost Regressor (XGBR) combined with Leave-One-Out Cross-Validation (LOO-CV) is selected from four algorithms for modeling with the highest coefficient of determination R 2 of 0.87. The introduction of λ 2 improves the performance of the model. The dataset is divided into 15 groups based on different doping elements (such as Hf, Cu, Zr, etc.), among which TiNiCu is the most predictive component with the R 2 of 0.89. Over 500 TiNiCu components are randomly generated and predicted T hys. Based on the contour maps created from the prediction results, it is found that T hys is likely to decrease with the increase of Cu doping in general, and minimum T hys occurs when the Cu is about 15 at. %, which is consistent with the existing experimental results. Eventually, a potential T hys minimum (1.2 K) region of Ti x Ni y Cu z (58.3%≤ x ≤ 58.5%, 26.5%≤ y ≤ 27%, 14.8%≤ z ≤ 15.3%, x + y + z = 100%) SMA composition is predicted. Our study not only provides a potential selection of narrow T hys TiNi-based SMAs but also indicates combining of XGBoost and DFT calculation is an effective strategy for materials design. [ABSTRACT FROM AUTHOR]

Evaluation of colour change as a function of temperature was studied on twenty eight samples of bulk ternary thermochromic composites using varying concentrations of crystal violet lactone as a colour former, bisphenol A as a developer and tetradecanol as a co-solvent. A number of parameters describing the colour change – reflectance, trichromatic values X and Y , visual colour densities DX and DY , and several parameters in CIELAB space, were obtained as a function of temperature. From these functions, the colour contrast, temperature sensitive interval, rate of colour change and width of hysteresis loop as the characteristics of thermochromic composites were evaluated and compared. The results show that cumulative colour difference Δ E C , representing the length of the path of colour change in CIELAB space, might be the best parameter in such an evaluation. Taking into account both the rate of colour change and the width of hysteresis loop the best performing thermochromic system could be selected. [ABSTRACT FROM AUTHOR]

High latitude waters in the Southern Ocean can be near their freezing point and remain ice-covered throughout the year whereas lower latitude Southern Ocean waters have seasonal ice coverage and comparatively large (6 °C) annual temperature changes. The genus Trematomus (suborder Notothenioidei) is regarded primarily as a high latitude group because of its abundance there, they also inhabit the warmer regions in smaller numbers. Freeze avoidance in the notothenioids is linked to the presence of two antifreeze proteins (AFPs); the antifreeze glycoproteins (AFGPs) and antifreeze potentiating protein (AFPP), both of which adsorb to internal ice crystals inhibiting growth. Both high and low latitude trematomids possess sufficient AFP to lower their blood freezing point below that of seawater (− 1.9 °C). We investigated the contributions of AFGPs and AFPP to the blood freezing point depression to determine how they varied with depth, water temperature, and the presence of ice. High latitude trematomids had lower blood freezing points than those inhabiting lower latitude waters indicating differences in their freeze avoidance capacities. Lower freezing points were associated with higher levels of antifreeze activity due to higher levels of both AFGP and AFPP. Populations of Trematomus hansoni and Trematomus bernacchii from shallow depths appear more freeze avoidant than populations inhabiting deep, ice-free water based on their lower freezing points and higher antifreeze activities. Gel electrophoresis of the trichloroacetic acid-soluble AFGPs indicates that only high molecular weight isoforms, which contribute more to AFGP activity, vary across species as well as between individuals of a species. [ABSTRACT FROM AUTHOR]