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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 λ2 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 B19 and B19′ regions for any given composition in NiTi-based SMAs and accurately estimate the λ2 parameter.

Copyright of Food & Machinery is the property of Food & Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The thermodynamic and kinetic simulations based on the re-assessment of the thermodynamic and kinetic database of the Ni-Ti-Cu system were employed to predict the phenomena of mechanical alloying, spark plasma sintering and thermal properties of the intriguing Ni-Ti-Cu system. Thermodynamic calculations are presented for the stable and unstable phases of NiTiCu materials and support a correlation with the evolving microstructure during the technological process. Also, the thermal conductivity, the thermal diffusivity and the specific heat of spark plasma sintered and aged Cu-alloyed NiTi-based shape memory alloys (NiTiCu) with two compositions, Ni45Ti50Cu5 and Ni40Ti50Cu10, are evaluated and the influence of mechanical alloying and precipitates on thermal properties is discussed. Measurements of these thermal properties were carried out from 25 °C up to 175 °C using the laser flash method, as well as differential scanning calorimetry. The thermal hysteresis of the 20 mm diameter samples was between 8.8 and 24.5 °C. The observed T0 temperatures from DSC experimental transformation features are in reasonable accordance with the thermodynamic predictions. The determined k values are between 20.04 and 26.87 W/m K and in agreement with the literature results. Moreover, this paper can provide some suggestions for the preparation of NiTiCu shape memory alloys and their applications. [ABSTRACT FROM AUTHOR]

Highlights: Cryopreservation generates ice recrystallization. D. antarctica apoplastic proteins show antifreeze activity. PMI of S. salar sperm can be maintained with AFPs. High MMP of sperm increases with AFPs. D. antarctica apoplastic proteins act as nonpermeable cryoprotectants. Antifreeze proteins (AFPs) are natural biomolecules found in cold-adapted organisms that lower the freezing point of water, allowing survival in icy conditions. These proteins have the potential to improve cryopreservation techniques by enhancing the quality of genetic material postthaw. Deschampsia antarctica, a freezing-tolerant plant, possesses AFPs and is a promising candidate for cryopreservation applications. In this study, we investigated the cryoprotective properties of AFPs from D. antarctica extracts on Atlantic salmon spermatozoa. Apoplastic extracts were used to determine ice recrystallization inhibition (IRI), thermal hysteresis (TH) activities and ice crystal morphology. Spermatozoa were cryopreserved using a standard cryoprotectant medium (C+) and three alternative media supplemented with apoplastic extracts. Flow cytometry was employed to measure plasma membrane integrity (PMI) and mitochondrial membrane potential (MMP) postthaw. Results showed that a low concentration of AFPs (0.05 mg/mL) provided significant IRI activity. Apoplastic extracts from D. antarctica demonstrated a cryoprotective effect on salmon spermatozoa, with PMI comparable to the standard medium. Moreover, samples treated with apoplastic extracts exhibited a higher percentage of cells with high MMP. These findings represent the first and preliminary report that suggests that AFPs derived from apoplastic extracts of D. antarctica have the potential to serve as cryoprotectants and could allow the development of novel freezing media. [ABSTRACT FROM AUTHOR]

Objective: Explore the cryoprotective mechanism and structure-activity relationship of antifreeze peptides derived from silver carp parvalbumin. Methods: Using differential scanning calorimetry and molecular dynamics simulation to compare activity, structure and mode of action of two typical peptides. Results: Pv-AFP 1 （KAADSFNH KAFFAKVG） had a stable α-helix structure, while Pv-AFP 2 （KAADSFNHKAF） tended to exhibit random coil. The thermal hysteresis activity of Pv-AFP 1 was 0.87 ℃, which was higher than Pv-AFP 2 （0.74 ℃）. Molecular dynamics simulations showed that Pv-AFP 1 could interact with 53 water molecules, and could form 16 hydrogen bonds to adsorb onto the surface of ice crystals, with a binding energy of -1 514 kJ/mol, all were greater than Pv-AFP 2 （can bind 50 water molecules, adsorb on ice surface by forming 11 hydrogen bonds, with a binding energy of -805 kJ/mol）. Despite the similarity of the two peptide sequences, their major sites and modes of interactions with water molecules and ice crystals were somewhat different. In addition, both peptides could interact with ice/water interface and altered the curvature of the ice surface, thereby inhibiting water freezing. But Pv-AFP 1 showed a better inhibitory effect on ice surface growth than Pv-AFP 2, which was consistent with their thermal hysteresis activity. Conclusion: The activities of antifreeze peptides derived from silver carp parvalbumin might be related to their structural characters and their affinities, sites and modes of interaction with water molecules and ice crystals.

Temperature‐modulated colloidal phase of plasmonic nanoparticles is a convenient playground for resettable soft‐actuators or colorimetric sensors. To render reversible clustering under temperature change, bulky ligands are required, especially if anisotropic morphologies are of interest. This study showcases thermoresponsive gold nanorods by employing small surface ligands, bis (p‐sulfonatophenyl) phenyl‐phosphine dihydrate dipotassium salt (BSPP) and native cationic surfactant. Temperature‐dependent analysis in real‐time allowed to describe the structural features (interparticle distance and cluster size) as well as thermal parameters, melting and freezing temperatures. These findings suggest that neither covalent Au−S bonds nor bulky ligands are required to obtain a robust thermoresponsive system based on anisotropic gold nanoparticles, paving the way to stimuli‐responsive nanoparticles with a wide range of sizes and geometries. [ABSTRACT FROM AUTHOR]

We measured the temperature dependence of the resistance in thinned samples of a layered transition metal dichalcogenide 1T-TiSe2. As a result, a thermal hysteresis of resistance was discovered in most samples with a thickness of 10 μm or less, but not in samples thicker than 100 μm. The onset temperature of this hysteresis was almost the same as the onset temperature of the charge density wave (CDW) transition, suggesting that this hysteresis is related to the CDW. All the samples with hysteresis exhibited one or a few jumps of resistance in the 110–190 K range in cooling. Moreover, the hysteresis was related not only to the history of temperature below the CDW transition temperature, but also to that above the transition temperature. To interpret these anomalous results, we discuss the effect of impurities on the domain structure of the CDW. [ABSTRACT FROM AUTHOR]

We measured the temperature dependence of the resistance in thinned samples of a layered transition metal dichalcogenide 1T-TiSe2. As a result, a thermal hysteresis of resistance was discovered in most samples with a thickness of 10 μm or less, but not in samples thicker than 100 μm. The onset temperature of this hysteresis was almost the same as the onset temperature of the charge density wave (CDW) transition, suggesting that this hysteresis is related to the CDW. All the samples with hysteresis exhibited one or a few jumps of resistance in the 110–190 K range in cooling. Moreover, the hysteresis was related not only to the history of temperature below the CDW transition temperature, but also to that above the transition temperature. To interpret these anomalous results, we discuss the effect of impurities on the domain structure of the CDW. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of the impurities effect in 2D spin crossover nanosystem in frame work of an Ising-like model. Results were obtained by means of Monte Carlo modeling technique, based on the heat bath algorithm. It is shown, that the impurities change the system’s thermal hysteresis width and shift the spin transition curves (HS → LS). In this manner, impurities can act as an additional influence parameter on the transition curves. The considered effect is not significant, but nevertheless should be taken into account in the developing process of nanoscale devices based on spin crossover compounds.

In the present work, the effects of Nb addition and aging on the microstructure evolution and martensitic transformation of (Ni50.3Ti28.7Hf20.0Sc1.0)100-xNbx (x = 0, 5, 10, 15 at.%) high temperature shape memory alloys were investigated. The addition of Nb results in the formation of the eutectic β-Nb phase along with martensite and Sc2O3 at room temperature. Aging at 550 °C for 3 h leads to the formation of nanoscale H-phase. The surface area fraction of the H-phase decreases with increasing Nb content to 10 at.%. As the Nb content increases, the transformation temperatures of the solution-treated NiTiHfScNb alloy increase and then decrease due to the variation of Ni content in the matrix. The aged samples show a smaller transformation hysteresis in comparison with the solution-treated samples. The difference of thermal hysteresis between the solution-treated and the aged samples increases with increasing Nb content because of the H-phase precipitation and Nb solution in matrix.

This research paper presents the results and analysis obtained via the evaluation of calcium nitrate as an effective stabilizer to alter the thermal properties as well as improve the compressive strength of frost-susceptible soil. Two silty sand soils with 15% and 25% fines content that are categorized as high to very high frost-susceptible soil were considered and treated with varying dosages of calcium nitrate contents (1.5%, 3.0%, 4.5%, 10%, 15%, and 20% of soil weight). The thermal properties, including thermal hysteresis, thermal conductivity, specific heat capacity, freezing point depression, and phase changes (freezing and thawing point) were determined for the untreated and treated soil samples. It was observed that the treated samples' thermal properties were significantly altered with respect to untreated soils. The effects of fines content on the thermal properties were evaluated using a stabilizer–silt content ratio. The threshold calcium nitrate dosage content was established, and a new correlation was established to evaluate the freezing point and thawing point. The unconfined compressive strength (UCS) tests performed on the treated soils depicted a significant increase in compressive strength compared to the untreated soil. Further analysis showed that fines content has a significant role to play on the compressive strength of treated silty sand. A qualitative analysis performed on images from a scanning electron microscope (SEM) showed that increasing the calcium nitrate dosage reduced the pore size and improved the cementation between the sand and silt grains. [ABSTRACT FROM AUTHOR]

Dehydrins exist widely in plants and play an important role in abiotic stress resistance. Two low-temperature-induced dehydrin-like genes, PmCAP and LpCAP, from the pine species Pseudotsuga menziesii and Larix principis-rupprechtii Mayr were cloned and found to contain 576 bp and 687 bp, encoding 191 and 228 amino acids, respectively. Both genes were individually assembled into prokaryotic expression vectors and transferred into E. coli cells. When transgenic stains were cultured at −5 °C, the lethal time 50% (LT50) was 50 h and 54 h for PmCAP and LpCAP, respectively, compared with 32 h for the control. When cultured at −20 °C, the LT50 was 38 h, 41 h, and 25 h for PmCAP, LpCAP, and the control. Thermal hysteresis (TH) testing of PmCAP and LpCAP proteins revealed TH values of 0.27 °C and 0.72 °C, respectively, relative to 0.05 °C for the BSA control. These results indicate that the two pine dehydrin proteins have antifreeze characteristics and that their antifreeze levels were well in relation to the environmental conditions of pine growth (Larix principis-rupprechtii Mayr mostly grows in cold and high-altitude zones, while Pseudotsuga menziesii grows in temperate and low-altitude zones). LpCAP, especially, could be a better gene resource for the molecular breeding of plant cold resistance. [ABSTRACT FROM AUTHOR]

Main conclusion: Conjugated sugars showed antifreeze activity in the cuticle by ice recrystallization inhibition rather than thermal hysteresis, enhancing freezing capacity at the surface of B. juncea leaves. Antifreeze biomolecules play a crucial role in mitigating the physical damage from frost by controlling extracellular ice crystal growth in plants. Antifreeze proteins (AFPs) are reported from the apoplast of different plants. Interestingly, there is no report about antifreeze properties of the cuticle. Here, we report the potential antifreeze activity in the Brassica juncea (BJ) leaf cuticle. Nano LC-MS/MS analysis of a cuticle protein enriched fraction (CPE) predicted over 30 putative AFPs using CryoProtect server and literature survey. Ice crystal morphology (ICM) and ice recrystallization inhibition (IRI) analysis of ABC supernatant showed heat and pronase-resistant, non-protein antifreeze activities as well as hexagonal ice crystals with TH of 0.17 °C and IRI 46%. The ZipTip processed ABC supernatant (without peptides) had no effect on TH activity, confirming a non-protein antifreeze molecule contributing to activity. To understand the origin and to confirm the source of antifreeze activity, cuticular membranes were isolated by pectinase and cellulase hydrolysis. FTIR analysis of the intact cuticle showed xylose, mannose, cellulose, and glucose. Xylanase and cellulase treatments of the ZipTip processed ABC supernatant led to an increase in sugar content and 50% loss in antifreeze activity. UV spectroscopy and NMR analysis supported the finding of FTIR and enzyme hydrolysis suggesting the contribution of xylose and mannose to antifreeze activity. By TLC analysis, conjugated sugars were found in the cuticle. This work has opened up a new research area where the antifreeze capacity needs to be established with regard to complete characterization and mechanism of action of the antifreeze carbohydrates (conjugated sugars) on the leaf surface. [ABSTRACT FROM AUTHOR]

The thermodynamic and kinetic simulations based on the re-assessment of the thermodynamic and kinetic database of the Ni-Ti-Cu system were employed to predict the phenomena of mechanical alloying, spark plasma sintering and thermal properties of the intriguing Ni-Ti-Cu system. Thermodynamic calculations are presented for the stable and unstable phases of NiTiCu materials and support a correlation with the evolving microstructure during the technological process. Also, the thermal conductivity, the thermal diffusivity and the specific heat of spark plasma sintered and aged Cu-alloyed NiTi-based shape memory alloys (NiTiCu) with two compositions, Ni45Ti50Cu5 and Ni40Ti50Cu10, are evaluated and the influence of mechanical alloying and precipitates on thermal properties is discussed. Measurements of these thermal properties were carried out from 25 °C up to 175 °C using the laser flash method, as well as differential scanning calorimetry. The thermal hysteresis of the 20 mm diameter samples was between 8.8 and 24.5 °C. The observed T0 temperatures from DSC experimental transformation features are in reasonable accordance with the thermodynamic predictions. The determined k values are between 20.04 and 26.87 W/m K and in agreement with the literature results. Moreover, this paper can provide some suggestions for the preparation of NiTiCu shape memory alloys and their applications.

Antifreeze proteins (AFPs) are natural biomolecules found in cold-adapted organisms that lower the freezing point of water, allowing survival in icy conditions. These proteins have the potential to improve cryopreservation techniques by enhancing the quality of genetic material postthaw. Deschampsia antarctica, a freezing-tolerant plant, possesses AFPs and is a promising candidate for cryopreservation applications. In this study, we investigated the cryoprotective properties of AFPs from D. antarctica extracts on Atlantic salmon spermatozoa. Apoplastic extracts were used to determine ice recrystallization inhibition (IRI), thermal hysteresis (TH) activities and ice crystal morphology. Spermatozoa were cryopreserved using a standard cryoprotectant medium (C+) and three alternative media supplemented with apoplastic extracts. Flow cytometry was employed to measure plasma membrane integrity (PMI) and mitochondrial membrane potential (MMP) postthaw. Results showed that a low concentration of AFPs (0.05 mg/mL) provided significant IRI activity. Apoplastic extracts from D. antarctica demonstrated a cryoprotective effect on salmon spermatozoa, with PMI comparable to the standard medium. Moreover, samples treated with apoplastic extracts exhibited a higher percentage of cells with high MMP. These findings represent the first and preliminary report that suggests that AFPs derived from apoplastic extracts of D. antarctica have the potential to serve as cryoprotectants and could allow the development of novel freezing media.

Thermal error is the main factor that affects the machining accuracy of the machine tools. Error compensation is a convenient and efficient method to reduce the effect of thermal error, and the compensation effect largely depends on the performance of the thermal error model. It is found that the thermal error has an obvious thermal hysteresis effect, and the current thermal error is affected by the previous temperature. Therefore, the thermal hysteresis effect is considered in the thermal error modeling. In this paper, the segmented modeling of the thermal error with variable lag order is studied. Firstly, the thermal characteristics of the spindle system of the gear grinding machine are analyzed and the X-directional thermal hysteresis of the gear grinding machine is theoretically demonstrated. Secondly, according to the temperature-thermal error relationship sketch combined with fuzzy cluster means (FCM) and correlation coefficient, the temperature sensitive points are selected. Thirdly, considering the variable lag order of thermal hysteresis, the lag orders of the heating and cooling processes in every cycle are calculated by particle swarm optimization (PSO). Fourthly, the distributed lag (DL) calculated by the PSO and multiple linear regression (MLR) is used to establish the model in different states, respectively. The S-PSO-DL model is obtained by combining all the segmented models. Compared with the segmented DL model established by mean lag order of inflection point (S-MLO-DL), the segmented back propagation neural network (S-BPNN), the segmented MLR model (S-MLR), and the no-segmented PSO-DL, the maximum residual of the prediction result of S-PSO-DL reduces by 40.8%, 60.0% and 72.8%, 46.3%. Finally, the thermal error of the gear grinding machine spindle is compensated, and the compensation rate of the model reaches 74.3%. [ABSTRACT FROM AUTHOR]

One of the greatest concerns in the subzero storage of cells, tissues, and organs is the ability to control the nucleation or recrystallization of ice. In nature, evidence of these processes, which aid in sustaining internal temperatures below the physiologic freezing point for extended periods of time, is apparent in freeze-avoidant and freeze-tolerant organisms. After decades of studying these proteins, we now have easily accessible compounds and materials capable of recapitulating the mechanisms seen in nature for biopreser-vation applications. The output from this burgeoning area of research can interact synergistically with other novel developments in the field of cryobiology, making it an opportune time for a review on this topic. [ABSTRACT FROM AUTHOR]

Shale gas production has become the main driver of global gas production growth. Deep shale gas is difficult to extract, which puts forward higher requirements for drilling speed increase. The downhole power drilling tools are mainly screw drilling tools. Conventional screw drill tool stator bushing has poor heat dissipation, which is prone to thermal hysteresis failure, shortening drilling tool life, and is not suitable for high temperature and high pressure environment of deep shale gas wells. Equal wall thickness screw drilling tools and hydrogenated nitrile rubber have better high temperature resistance. Therefore, based on the thermal aging experiment and constitutive model of the rubber changes the displacement of the inner cavity of the stator bushing and the difference between the front and the back is up to 21.6%. The increase of the interference and eccentricity between rotor and motor leads to the increase of the maximum von Mises stress of the stator bushing and the thermal hysteresis temperature. The influence of the interference is greater than the influence of the eccentricity so that the interference should be given priority in the design. This paper provides a theoretical reference for the design and optimization of equal wall thickness bushing of positive displacement motor.

The aim of this paper is the development of a qualitative understanding of thermal hysteresis, namely the difference between the melting T m and solidification T s temperatures of nanoparticles as a function of the particle size. In contrast to the melting temperature, the determination of the absolute value of the solidification temperature for nanoparticles is generally more difficult and subjected to significant uncertainties. In this study, we implemented a very generic approach based on classical nucleation theory and define the thermal hysteresis for a nanoparticle relative to its value for a much larger 'reference' particle made of the same material. The obtained thermal hysteresis is found to vanish when decreasing the nanoparticle size. The approach is illustrated using the examples of gold, bismuth, and platinum nanoparticles. [ABSTRACT FROM AUTHOR]

Structural, magnetic, and electrical properties of La0.5Ca0.5MnO3 samples prepared at two different sintering temperatures (800°C and 1350°C which were labeled S800 and S1350, respectively) have been investigated. The Reitveled refined XRD patterns indicate an orthorombic structure with Pnma space group for both samples. Ac susceptibility measurements show that, the fraction of ferromagnetic and antiferromagnetic phases could be controlled with sintering temperature. S800 sample has a ferromagnetic state while the antiferromagnetic phase is enhanced in S1350 sample which causes the increase of thermal hysteresis in this sample. Two distinct regions (T>ӨD/2 and T˂ӨD/2, ӨD is the Debye’s temperature) were noticed to investigate the electrical properties. Based on the resistivity data at T>ӨD/2 region, the S800 and S1350 samples follow the adiabatic and non-adiabatic small polaron hopping (SPH) models, respectively. At T˂ӨD/2 region, the 3-dementional variable range hopping (VRH) model displays a good correlation with the experimental data of both samples. The related parameters of both SPH and VRH models are extracted. The results show that these parameters are particle size dependent.

The role of temperature on biological activities and the correspondent exponential relationship with temperature has been known for over a century. However, lacking to date is knowledge relating to (a) the recovery of ectotherms subjected to extreme temperatures in the wild, and (b) the effects repeated extreme temperatures have on the temperatures that induce behavioural thermoregulation (aggregations). We examined these questions by testing the hypothesis that thermal thresholds which initiate aggregations in juvenile Atlantic salmon (AS) (Salmo salar) are not static, but are temporally dynamic across a summer and follow a hysteresis loop. To test our hypothesis, we deployed custom-made underwater camera (UWC) systems in known AS thermal refuges to observe the timing of aggregation events in a natural system and used these data to develop and test models that predict the temperatures that induce thermal aggregations. Consistent with our hypothesis our UWC observations revealed a range of aggregation onset temperatures (AOT) ranging from 24.2°C to 27.1°C, thus confirming our hypothesis that AOTs are dynamic across summer. Our models suggest it take ~ 11 days of non-thermally taxing temperatures for the AOT to rebound in the study river. Conversely, we found that as the frequency of events increased, the AOT declined, from 27.1°C to 24.2°C. Integrating both model components led to more robust model performance. Further, when these models were tested against an independent data set from the same river, the results remained robust. Our findings illustrate the complexity underlying behavioural thermoregulation in AS—a complexity that most likely extends to other salmonids. The frequency of extreme heat events is predicted to increase, and this has the capacity to decrease AOT thresholds in AS, ultimately reducing their resilience to extreme temperature events. [ABSTRACT FROM AUTHOR]

The hysteretic behavior of shape memory alloys (SMA) is technologically important and advantageous in some applications but detrimental in others. In this paper, the effect of stress on the thermal hysteresis of SMA during the martensite transformation is studied. A recently developed discrete particle approach referred to as the continuum based particle dynamics (CPD) is used for this study. The CPD model uses a multibody interactions among the discrete particles which is directly derived from poly-convex free energy pertinent to such material behaviors. In the analysis, temperature of the domain is considered as the control parameter and is varied uniformly through out the domain above and below the transformation temperature. The hysteresis response resulting from this thermal cycle is observed in specific heat-temperature plot (DSC curve) and strain-temperature plot. The effect of prestress on thermal hysteresis along with the corresponding martensite microstructure is modeled. The results show a decrease in hysteresis with increased stress. This effect is attributed to the force required to propagate the ledges along the twin or phase boundary, which is smaller for the stressed material as compared to the stress–free material. [ABSTRACT FROM AUTHOR]

It is well known that CsCl‐type FeRh undergoes from antiferromagnetic (AFM) to ferromagnetic (FM) phase transition near room temperature with large thermal hysteresis. Therefore, it is particularly essential to find new methods to manipulate the magnetic order of FeRh and reduce thermal hysteresis. Herein, the magnetic phase transition of FeRh film by applying a low‐frequency in‐plane alternating current (AC) magnetic field is successfully manipulated. It is found that under the AC magnetic field, the phase transition of the FM–AFM is promoted, and the heating branch shifts at a rate of −8 K T−1, which causes the thermal hysteresis of FeRh reduction of about 2 K. These phenomena may be attributed to the Zeeman energy and the periodic vibration of domain walls. This work provides the possibility for the realization of low‐power spintronic devices. [ABSTRACT FROM AUTHOR]

Spin-crossover solids have been studied for many years for their promising applications as optical switches and reversible high-density memories for information storage. This study reports the effect of random metal dilution on the thermal and structural properties of a spin-crossover single crystal. The analysis is performed on a 2D rectangular lattice using an electro-elastic model. The lattice is made of sites that can switch thermally between the low-spin and high-spin states, accompanied by local volume changes. The model is solved by Monte Carlo simulations, running on the spin states and atomic positions of this compressible 2D lattice. A detailed analysis of metal dilution on the magneto-structural properties allows us to address the following issues: (i) at low dilution rates, the transition is of the first order; (ii) increasing the concentration of dopant results in a decrease in cooperativity and leads to gradual transformations above a threshold concentration, while incomplete spin transitions are obtained for big dopant sizes. The effects of the metal dilution on the spatiotemporal aspects of the spin transition along the thermal transition and on the low-temperature relaxation of the photo-induced metastable high-spin states are also studied. Significant changes in the organization of the spin states are observed for the thermal transition, where the single-domain nucleation caused by the long-range elastic interactions is replaced by a multi-droplet nucleation. As to the issue of the relaxation curves: their shape transforms from a sigmoidal shape, characteristic of strong cooperative systems, into stretched exponentials for high dilution rates, which is the signature of a disordered system. [ABSTRACT FROM AUTHOR]

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]

Dehydrins exist widely in plants and play an important role in abiotic stress resistance. Two low-temperature-induced dehydrin-like genes, PmCAP and LpCAP, from the pine species Pseudotsuga menziesii and Larix principis-rupprechtii Mayr were cloned and found to contain 576 bp and 687 bp, encoding 191 and 228 amino acids, respectively. Both genes were individually assembled into prokaryotic expression vectors and transferred into E. coli cells. When transgenic stains were cultured at −5 °C, the lethal time 50% (LT50) was 50 h and 54 h for PmCAP and LpCAP, respectively, compared with 32 h for the control. When cultured at −20 °C, the LT50 was 38 h, 41 h, and 25 h for PmCAP, LpCAP, and the control. Thermal hysteresis (TH) testing of PmCAP and LpCAP proteins revealed TH values of 0.27 °C and 0.72 °C, respectively, relative to 0.05 °C for the BSA control. These results indicate that the two pine dehydrin proteins have antifreeze characteristics and that their antifreeze levels were well in relation to the environmental conditions of pine growth (Larix principis-rupprechtii Mayr mostly grows in cold and high-altitude zones, while Pseudotsuga menziesii grows in temperate and low-altitude zones). LpCAP, especially, could be a better gene resource for the molecular breeding of plant cold resistance.

This article describes thermal input/concentration output systems processed by chemical reactions. Various sophisticated thermal inputs can be converted into concentration outputs through the double-helix formation of helicene oligomers exhibiting thermal hysteresis. The inputs include high or low temperature, cooling or heating state, slow or fast cooling state, heating state, and cooling history. The chemical basis for the properties of the chemical reactions includes the reversibility out of chemical equilibrium, sigmoidal relationship and kinetics, bistability involving metastable states, positive feedback by self-catalytic chemical reactions, competitive chemical reactions, and fine tunability for parallel processing. The interfacing of concentration outputs in other systems is considered, and biological cells are considered to have been utilizing such input/output systems processed by chemical reactions.

The entropy changes in successive martensitic phase transformations in Ni-Mn-Ga Heusler alloys can be used to realize enhanced magnetocaloric properties. A detailed study of phase transformations of one such alloy, Ni2.15Mn0.85Ga ($\Delta Q =4900$ J/kg at 343 K, under 140 kOe), is reported here. Upon cooling, the paramagnetic cubic (L21) austenitic phase transforms into a ferromagnetic 7M modulated monoclinic martensitic phase. This phase is stable in a narrow temperature range, and upon further cooling, it transforms into a non-modulated ferromagnetic tetragonal (L10) phase. The separation between the equilibrium temperatures of the austenitic and tetragonal martensitic phases is only ~50 K. The alloy undergoes reversible temperature-induced martensitic and inter-martensitic phase transformations with thermal hysteresis of about 25 K. The conclusions from the detailed study of the phase transformations lead to new possibilities to enhance the magnetocaloric effect (MCE) using the entropy associated with multi-structural transformations. [ABSTRACT FROM AUTHOR]

Magnetic cooling, a solid-state refrigeration technology based on the magnetocaloric effect, has attracted significant attention in space cooling due to its high energy-efficiency and environmental friendliness. Transition metal-based magnetocaloric materials (MCMs) with the merit of low-cost have emerged as promising candidates for efficient magnetic refrigeration applications. This review explores the intricate relationship between microstructure and multiple properties (e.g. magnetocaloric properties, mechanical stability, thermal conductivity, and functional reversibility) of these materials. A variety of microstructural manipulation approaches (e.g. crystallographic texture, precipitates, micropores, atomic-scale defects, size effect, and composites) are examined for their effects on the comprehensive performance of MCMs. We show that microstructure design provides an effective tool to achieve excellent performance in multiple aspects, which may facilitate the commercialization of transition-metal based MCMs., (Creative Commons Attribution license.)

This article presents experimental results and analysis of change in freezing characteristics of clays and silts with change in pH and moisture content in the pore structures. The plastic and non-plastic silts and clays in the cold regions undergo significant changes in thermal properties causing non-equilibrium thermal conditions which can lead to frost-heave, thaw-weakening, thawing-induced landslides, and mass wasting events. In geotechnical engineering, particularly in cold regions, a soil’s thermal properties play a large role in the design, functionality, and longevity of an earthen structure. The thermal properties of the soil will also govern the porous media phase changes influencing thermal hysteresis and heat capacity in soils. These variables will change with seasonal freeze–thaw cycles, which can lead to changes in a soil’s structure, fabric, density, moisture content, and strength over time. With global warming causing the temperatures to gradually rise over time, the rapidly varying seasonal freeze–thaw cycles are now becoming an issue in areas where the designs have relied heavily on the permafrost. This research study investigates the fundamental changes to freezing and thawing characteristics of plastic and non-plastic silts with changes in frost penetration rates (cooling rate); moisture content (liquid limit, plastic limit, and optimum moisture content); pH (2–7); and soil type with different percentages of fines content and specific surface area.

• 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]

The aim of this paper is the development of a qualitative understanding of thermal hysteresis, namely the difference between the melting Tm and solidification Ts temperatures of nanoparticles as a function of the particle size. In contrast to the melting temperature, the determination of the absolute value of the solidification temperature for nanoparticles is generally more difficult and subjected to significant uncertainties. In this study, we implemented a very generic approach based on classical nucleation theory and define the thermal hysteresis for a nanoparticle relative to its value for a much larger ‘reference’ particle made of the same material. The obtained thermal hysteresis is found to vanish when decreasing the nanoparticle size. The approach is illustrated using the examples of gold, bismuth, and platinum nanoparticles.

A temperature-dependent Raman experiment between 80 and 600 K was performed in a nanoparticulated coating of single-phase hematite grown on a silica substrate. In that range, a thermal Raman shift hysteresis was identified in the vibrational modes that accompanies the Morin transition, observing large effects in the two-magnon Raman frequency position and in its relative intensity. Interestingly, no decrease in coercivity occurs when the hematite crosses the Morin transition below 230 K. The spin-flop processes produced in the coating leads to a strong decompensation of the surface spins, generating a ferromagnetic component over the whole temperature range studied. Such unusual effects might be promoted by a certain degree of structural disorder and the stresses produced by the nanoparticulation growth approach of the hematite coating. As a result, a high stability of the two-magnon excitation is obtained over a wide temperature range and considerable advances are made for the development of spintronic devices based on semiconductor antiferromagnetic materials. [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]

This article describes thermal input/concentration output systems processed by chemical reactions. Various sophisticated thermal inputs can be converted into concentration outputs through the double-helix formation of helicene oligomers exhibiting thermal hysteresis. The inputs include high or low temperature, cooling or heating state, slow or fast cooling state, heating state, and cooling history. The chemical basis for the properties of the chemical reactions includes the reversibility out of chemical equilibrium, sigmoidal relationship and kinetics, bistability involving metastable states, positive feedback by self-catalytic chemical reactions, competitive chemical reactions, and fine tunability for parallel processing. The interfacing of concentration outputs in other systems is considered, and biological cells are considered to have been utilizing such input/output systems processed by chemical reactions. [ABSTRACT FROM AUTHOR]