Insight into the structure-activity relationship of thermal hysteresis activity of cod collagen peptides through peptidomics and bioinformatics approaches.

To elucidate the correlation between variations in thermal hysteresis activity (THA) and the physicochemical properties and structure, antifreeze peptides (AFPs) of isolated fractions (CCP-1 and CCP-2) were characterized on based peptidomics and bioinformatics. The results revealed a positive correlation between the THA of cod collagen antifreeze peptide (CCAFP) and peptide chain length, isoelectric point, and hydrophobic amino acid content. Notably, the THA of CCP-1, which has higher alkaline amino acid content, was 2.60 °C at a concentration of 10 mg/mL, significantly higher than CCP (1.90 °C) and CCP-2 (2.27 °C). Glycine, proline, and valine were the vital amino acids to the formation of hydrogen bonds. Conversely, aspartic and glutamic acids at terminal regions of AFPs tended to introduce kinks in their structures. This distortion reduced binding sites for ice crystals, thereby decreasing their THA, providing a theory for understanding the physicochemical properties and structure of AFPs that influence their THA.

The cryoprotective effect of Litopenaeus vannamei head-derived peptides and its ice-binding mechanism.

Although discarded as waste, shrimp heads are a potential source of antifreeze peptides, which can be used as cryoprotectants in the food industry. Their utilization in frozen foods can help mitigate the negative effects caused by the freezing technique. Litopenaeus vannamei shrimp heads were autolyzed, and the shrimp head autolysate (SHA) was separated via ultra-filtration and ion exchange chromatography. The antifreeze effect of SHA on the biochemical properties of myofibrillar proteins of peeled shrimps during five freeze-thaw cycles was evaluated. Peptide screening was done using the LC-MS/MS technique. A molecular docking (MD) study of the interaction between ice and shrimp head-derived antifreeze peptides was done. Results showed that shrimp-head autolysate has a maximum thermal hysteresis value of 1.84 °C. During the freeze-thaw cycles, the shrimp-head autolysate exhibited an antifreeze effect on frozen peeled shrimps. 1.0 and 3.0%-SHA groups showed significantly lower freeze denaturation than the negative control group. The muscle tissues of SHA-treated groups were not as severely damaged as the negative control group. The molecular docking study revealed that the shrimp head-AFPs bound to ice via hydrogen bonding, and both hydrophilic and hydrophobic amino acid residues were involved in the ice-binding interactions. 6 ice-binding sites were involved in the peptide-ice interaction. Our findings suggest that shrimp head-derived AFPs can be developed into functional additives in frozen foods and add more insights into the existing literature on antifreeze peptides.

Room-temperature magnetocapacitance spanning 97 K hysteresis in molecular material.

Magnetic capacitor, as a new type of device, has broad application prospects in fields such as magnetic field sensing, magnetic storage, magnetic field control, power electronics and so on. Traditional magnetic capacitors are mostly assembled by magnetic and capacitive materials. Magnetic capacitor made of a single material with intrinsic properties is very rare. This intrinsic property is magnetocapacitance (MC). The studies on MC effect have mainly focused on metal oxides so far. No study was reported in molecular materials. Herein, two complexes: (CETAB)2[CuCl4] (1) and (CETAB)2[CuBr4] (2) (CETAB = (2-chloroethyl)trimethylammonium) are reported. There exist strong H-Br and Br-Br interactions and other weak interactions in complex 2, so the phase transition energy barrier is high, resulting in the widest thermal hysteresis loop on a molecular level to date. Furthermore, complexes 1 and 2 show large MC parameters of 0.247 and 1.614, respectively, which is the first time to observe MC effect in molecular material.

A brief review of microstructure design in transition metal-based magnetocaloric materials.

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.

On the engulfment of antifreeze proteins by ice.

Antifreeze proteins (AFPs) are remarkable biomolecules that suppress ice formation at trace concentrations. To inhibit ice growth, AFPs must not only bind to ice crystals, but also resist engulfment by ice. The highest supercooling, [Formula: see text], for which AFPs are able to resist engulfment is widely believed to scale as the inverse of the separation, [Formula: see text], between bound AFPs, whereas its dependence on the molecular characteristics of the AFP remains poorly understood. By using specialized molecular simulations and interfacial thermodynamics, here, we show that in contrast with conventional wisdom, [Formula: see text] scales as [Formula: see text] and not as [Formula: see text]. We further show that [Formula: see text] is proportional to AFP size and that diverse naturally occurring AFPs are optimal at resisting engulfment by ice. By facilitating the development of AFP structure-function relationships, we hope that our findings will pave the way for the rational design of AFPs.

Acoustic Wave-Induced FeRh Magnetic Phase Transition and Its Application in Antiferromagnetic Pattern Writing and Erasing.

We explore the FeRh magnetic phase transition (MPT) and magnetic phase domain (MPD) with the introduction of surface acoustic waves (SAWs). The effects of the SAW pulses with different pulse widths and powers on resistance-temperature loops are investigated, revealing that the SAW can reduce the thermal hysteresis. Meanwhile, the SAW-induced comb-like antiferromagnetic (AFM) phase domains are observed. By changing the pulse width and SAW frequency, we further realize a writing-erasing process of the different comb-like AFM phase domains in the mixed-phase regime of the cooling transition branch. Resistance measurements also display the repeated SAW writing-erasing and the nonvolatile characteristic clearly. MPT paths are measured to demonstrate that short SAW pulses induce isothermal MPT and write magnetic phase patterns via the dynamic strain, whereas long SAW pulses erase patterns via the acoustothermal effect. The Preisach model is introduced to model the FeRh MPT under the SAW pulses, and the calculated results correspond well with our experiments, which reveals the SAW-induced energy modulation promotes FeRh MPT. COMSOL simulations of the SAW strain field also support our results. Our study not only can be used to reduce the thermal hysteresis but also extends the application of the SAW as a tool to write and erase AFM patterns for spintronics and magnonics.

Thermodynamic and Kinetic Simulations Used for the Study of the Influence of Precipitates on Thermophysical Properties in NiTiCu Alloys Obtained by Spark Plasma Sintering.

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.

Novel Apoplastic Antifreeze Proteins of Deschampsia antarctica as Enhancer of Common Cell Freezing Media for Cryobanking of Genetic Resources, a Preliminary Study.

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.

Engineered ice-binding protein (FfIBP) shows increased stability and resistance to thermal and chemical denaturation compared to the wildtype.

Many polar organisms produce antifreeze proteins (AFPs) and ice-binding proteins (IBPs) to protect themselves from ice formation. As IBPs protect cells and organisms, the potential of IBPs as natural or biological cryoprotective agents (CPAs) for the cryopreservation of animal cells, such as oocytes and sperm, has been explored to increase the recovery rate after freezing-thawing. However, only a few IBPs have shown success in cryopreservation, possibly because of the presence of protein denaturants, such as dimethyl sulfoxide, alcohols, or ethylene glycol, in freezing buffer conditions, rendering the IBPs inactive. Therefore, we investigated the thermal and chemical stability of FfIBP isolated from Antarctic bacteria to assess its suitability as a protein-based impermeable cryoprotectant. A molecular dynamics (MD) simulation identified and generated stability-enhanced mutants (FfIBP_CC1). The results indicated that FfIBP_CC1 displayed enhanced resistance to denaturation at elevated temperatures and chemical concentrations, compared to wildtype FfIBP, and was functional in known CPAs while retaining ice-binding properties. Given that FfIBP shares an overall structure similar to DUF3494 IBPs, which are recognized as the most widespread IBP family, these findings provide important structural information on thermal and chemical stability, which could potentially be applied to other DUF3494 IBPs for future protein engineering.

Temperature-Modulated Reversible Clustering of Gold Nanorods Driven by Small Surface Ligands.

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.

Paradoxical effects on ice nucleation are intrinsic to a small winter flounder antifreeze protein.

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.

Datasets of narrow thermal hysteresis behaviour Ti-Ni-based HT-SMAs and the predicted accumulated local effects.

This article refers to data derived from a research article entitled "Prediction of narrow HT-SMA thermal hysteresis behaviour using explainable machine learning" [1]. It is based on the knowledge that alloying Ti-Ni-based shape memory alloys (SMAs) with additional ternary or multicomponent elements can alter the SMAs' characteristic transformation temperatures, including the thermal hystereses. Two datasets are reported. The first and primary dataset documents experimental Ti-Ni-based shape memory alloys' high-transformation temperature characteristics reported in the literature. The second auxiliary dataset presented in this article was obtained following the explainable prediction of the narrow high-temperature thermal hysteresis behaviour in Ti-Ni-based high-transformation temperature SMAs (HT-SMAs). The second dataset is intended to generalise and summarise the ML prediction and visualisation of the thermal hysteresis behaviour as also observed experimentally in multiple reports elsewhere. The datasets are provided as supplementary files and the second dataset is also visualised as an intuitive marginal effects plot. We believe that these data will find applications in advancing experimental and theoretical HT-SMA research.

Brassica juncea leaf cuticle contains xylose and mannose (xylomannan) which inhibit ice recrystallization on the leaf surface.

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.

Engineered Compounds to Control Ice Nucleation and Recrystallization.

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.

Timing and frequency of high temperature events bend the onset of behavioural thermoregulation in Atlantic salmon (Salmo salar).

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.

Quinoa protein Pickering emulsion: A promising cryoprotectant to enhance the freeze-thaw stability of fish myofibril gels.

In this work, the effects of different QPE addition on the freeze-thaw (F-T) stability of fish myofibrillar protein (MP) gels were revealed. During freezing process, QPE decreased the freezing point of MP gels and shortened the time to pass through the maximum-ice-crystal-formation zone. The occurrence of thermal hysteresis effect led to the formation of small ice crystals and alleviated the damage to MP gel network. The incorporation of 7.5% QPE also reduced the free water amount to 19.23% and improved the water holding capacity of MP gels. Furthermore, the incorporation of QPE decreased the carbonyl content of MP gels after F-T cycles and delayed the protein oxidation. Meanwhile, QPE addition maintained the stability of the tertiary structure of MP gels via stabilizing the microenvironment of tyrosine and tryptophan. Overall, QPE shows the potential as a new cryoprotectant to improve the F-T stability of MP gel products.

Screening and characterization of a novel antifreeze peptide from silver carp muscle hydrolysate.

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.

Electro-Elastic Modeling of Thermal Spin Transition in Diluted Spin-Crossover Single Crystals.

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.

Effect of antifreeze proteins on the freeze-thaw cycle of foods: fundamentals, mechanisms of action, current challenges and recommendations for future work.

Freezing is widely used in food preservation, but if not carried out properly, ice crystals can multiply (nucleation) or grow (recrystallization) rapidly. This also affects thawing, causing structural damage and affecting overall quality. The objective of this review is to comprehensively study the cryoprotective effect of antifreeze proteins (AFPs), highlighting their role in the freeze-thaw process of food. The properties of AFPs are based on their thermal hysteresis capacity (THC), on the modification of crystal morphology and on the inhibition of ice recrystallization. The mechanism of action of AFPs is based on the adsorption-inhibition theory, but the specific role of hydrogen and hydrophobic bonds/residues and structural characteristics is also detailed. Because of the properties of AFPs, they have been successfully used to preserve the quality of a wide variety of refrigerated and frozen foods. Among the limitations of the use of AFPs, the high cost of production stands out, but currently there are solutions such as the use the production of recombinant proteins, cloning and chemical synthesis. Although in vitro, in vivo and human studies have shown that AFPs are non-toxic, their safety remains a matter of debate. Further studies are recommended to expand knowledge about AFPs, to reduce costs in their large-scale production, to understand their interaction with other food compounds and their possible effects on the consumer.

Thermal Hysteresis and Ordering Behavior of Magnetic Skyrmion Lattices.

The physics of phase transitions in two-dimensional (2D) systems underpins research in diverse fields including statistical mechanics, nanomagnetism, and soft condensed matter. However, many aspects of 2D phase transitions are still not well understood, including the effects of interparticle potential, polydispersity, and particle shape. Magnetic skyrmions are chiral spin-structure quasi-particles that form two-dimensional lattices. Here, we show, by real-space imaging using in situ cryo-Lorentz transmission electron microscopy coupled with machine learning image analysis, the ordering behavior of Néel skyrmion lattices in van der Waals Fe3GeTe2. We demonstrate a distinct change in the skyrmion size distribution during field-cooling, which leads to a loss of lattice order and an evolution of the skyrmion liquid phase. Remarkably, the lattice order is restored during field heating and demonstrates a thermal hysteresis. This behavior is explained by the skyrmion energy landscape and demonstrates the potential to control the lattice order in 2D phase transitions.