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Structural disorder in mesoporous solids gives rise to complex phase behavior for materials confined within their pore spaces. As a result, a wide spectrum of possible phase configurations associated with spatial distributions of thermodynamic phases throughout the pore networks can be realized in experiments. Despite their importance, quantifying these states remains largely unaddressed. By considering solid–liquid equilibria as a representative example and using a simple random network model, we investigate the spectrum of such states accessible in real experiments and relate this spectrum to the structural characteristics of porous solids. We classify these states by their free energies and demonstrate how network effects break degeneracies for specific phase compositions and temperatures. Furthermore, we identify the experimental conditions that delineate boundary free energy states, differentiating accessible from inaccessible states. The insights from this study on solid–liquid equilibria are also equally applicable to gas–liquid equilibria in confined spaces and contribute to a deeper understanding of relaxation dynamics associated with hysteresis. [ABSTRACT FROM AUTHOR]

The Mpemba effect describes the phenomenon that a system at hot initial temperature cools faster than at an initial warm temperature in the same environment. Such an anomalous cooling has recently been predicted and realized for trapped colloids. Here, we investigate the freezing behavior of a passive colloidal particle by employing numerical Brownian dynamics simulations and theoretical calculations with a model that can be directly tested in experiments. During the cooling process, the colloidal particle exhibits multiple non-monotonic regimes in cooling rates, with the cooling time decreasing twice as a function of the initial temperature—an unexpected phenomenon we refer to as the Double Mpemba effect. In addition, we demonstrate that both the Mpemba and Double Mpemba effects can be predicted by various machine-learning methods, which expedite the analysis of complex, computationally intensive systems. [ABSTRACT FROM AUTHOR]

By employing brute-force molecular dynamics, umbrella sampling, and seeding simulations, we investigate homogeneous nucleation during melting and freezing of hard spheres. We provide insights into these opposing phase transitions from the standpoint of classical nucleation theory. We observe that melting has both a lower driving force and a lower interfacial tension than freezing. The lower driving force arises from the vicinity of a spinodal instability in the solid and from a strain energy. The lower interfacial tension implies that the Tolman lengths associated with melting and freezing have opposite signs, a phenomenon that we interpret with Turnbull's rule. Despite these asymmetries, the nucleation rates for freezing and melting are found to be comparable. [ABSTRACT FROM AUTHOR]

It is shown that the transport coefficients (self-diffusion, shear viscosity, and thermal conductivity) of the Weeks–Chandler–Andersen (WCA) fluid along isotherms exhibit a freezing density scaling (FDS). The functional form of this FDS is essentially the same or closely related to those in the Lennard-Jones fluid, hard-sphere fluid, and some liquefied noble gases. This proves that this FDS represents a quasi-universal corresponding state principle for simple classical fluids with steep interactions. Some related aspects, such as a Stokes–Einstein relation without a hydrodynamic diameter and gas-to-liquid dynamical crossover, are briefly discussed. Simple fitting formulas for the transport coefficients of the dense WCA fluid are suggested. [ABSTRACT FROM AUTHOR]

Vitrification is a promising approach for ice-free cryopreservation of biological material, but progress is hindered by the limited set of experimental tools for studying processes in the interior of the vitrified matter. Isochoric cryopreservation chambers are often metallic, and their opacity prevents direct visual observation. In this study, we introduce photon counting X-ray computed tomography (CT) to compare the effects of rigid isochoric and unconfined isobaric conditions on vitrification and ice formation during cooling of two aqueous solutions: 50 wt% DMSO and a coral vitrification solution, CVS1. Previous studies have only compared vitrification in isochoric systems with isobaric systems that have an exposed air-liquid interface. We use a movable piston to replicate the surface and thermal boundary conditions of the isochoric system yet maintain isobaric conditions. When controlling for the boundary conditions we find that similar ice and vapor volume fractions form during cooling in isochoric and isobaric conditions. Interestingly, we observe distinct ice and vapor cavity morphology in the isochoric systems, possibly due to vapor outgassing or cavitation as rapid cooling causes the pressure to drop in the confined systems. These observations highlight the array of thermal-fluid processes that occur during vitrification in confined aqueous systems and motivate the further application of imaging techniques such as photon counting X-ray CT in fundamental studies of vitrification.

Ice crystal growth of water and its aqueous solution is the key phenomenon in food freezing. In this research, the effect of static magnetic field (SMF) on single ice crystal growth was investigated combing experiment and simulation. The ice crystal growth of water and NaCl-water solution under 0 - 15 mT SMF intensities were studied. The UV absorbance of water after SMF treatment was measured. Phase field model was adopted to simulate the ice crystal growth. The results show that SMF significantly inhibited the growth rate, while had little effect on the morphology and growth direction of ice crystals. SMF had a certain enhancement effect on the UV absorbance of deionized water. The proposed model could well simulate the ice crystal growth under different SMF intensities. Combining experimental and simulation results, it can be inferred that SMF inhibits ice crystal growth by enhancing original hydrogen bonds and reducing free energy. [ABSTRACT FROM AUTHOR]

This study investigates the production of pasta filata style cheese from a storable, frozen intermediate material. Homogenization (2–16 MPa, single-staged) of milk (fat/protein = 0.9) was used as a tool to decrease fat globule size and consequently fat losses. Plasticization was achieved by using a single-screw extruder set up with double-jacketed hot water cycle. Non-frozen and frozen cheese curd as well as the extruded pasta filata style cheese pre-treated with different homogenization pressure was analyzed regarding the thermo-rheological properties. Fat and protein gain/loss during extrusion was evaluated by analyzing fat in dry matter (FDM) and protein in dry matter (PDM) before and after extrusion. Homogenization of cheese milk leads to a reduction of tan δ for thereof produced raw cheese curd material as well as the extruded products. Freezing and extrusion counteract the reduction of tan δ. A homogenization pressure of 8 MPa is sufficient to prevent fat losses during extrusion while still maintaining plasticization of the product for fresh and frozen material, respectively. The FDM after extrusion is 0.8% higher for fresh material and 4.9% higher for frozen material, which means that the fat concentrates during extrusion due to water loss. Moreover, there is no loss of PDM for all samples, regardless of the homogenization pressure. A combination of homogenization pressure, freezing, and extrusion leads to a plasticizable product without losses of fat and protein. Hence, frozen cheese curd can be used as a storable intermediate. [ABSTRACT FROM AUTHOR]

In very cold environments, it may be burdensome or impossible for the polar medic to prevent medicines from freezing. We sought to investigate whether orientation affected the risk that glass ampoules of 1 in 1000 adrenaline, an important emergency drug, would break during freezing and subsequent thawing. Ampoules of adrenaline were orientated either upright, horizontally or inverted. They were exposed to freezing temperatures (-25°C or -80°C) and then allowed to thaw. A crossover design was used whereby the orientation of unbroken ampoules was changed for the next trial. No ampoules broke when frozen at -25°C and then thawed. When this was repeated at -80°C, ampoules reliably broke unless they were upright with no liquid in the top part of the ampoule. Upright orientation prevents the breakage of glass ampoules of 1 in 1000 adrenaline rapidly frozen at -80°C. The polar medic may consider storing ampoules upright if they are to be exposed to very low temperatures. [ABSTRACT FROM AUTHOR]

Supercooling preservation of fruits and vegetables (FV) is critical to food freezing. Magnetic field (MF)-assisted freezing of FV promotes supercooling; but its phenomenon is yet to be uncovered. Therefore, information on the supercooling phenomenon of MF-assisted freezing and its impacts on the quality preservation of frozen FV is critical to cellular food freezing manufacturing practices. This study reported on the supercooling phenomenon of MF-assisted freezing and its impacts on the quality preservation of frozen FV. Intrinsic factors (hydrogen bonding ordering and geometry) related to product, and extrinsic factors (types of magnetic field, field intensity, and exposure time) related to process parameters, that influenced supercooling were discussed. The study revealed that the occurrence of supercooling during MF-assisted freezing depends mainly on the types of magnetic field applied, field intensity and the direction of the applied field, which affects the effective magnetic lines of force resulting to uncompensated electron spins through samples. The exhibition of electron spins increases the order of magnetic ions and water molecules contained in cellular foods. For process design, more in-depth study and accurate understanding of the supercooling phenomenon of MF-assisted freezing and its impacts on the quality preservation of frozen FV are essential. It is hoped that this study provide better insight on the supercoling phenomenon of MF-assisted freezing and its impacts on the quality preservation of frozen FV for further studies. Practical Applications: Application of high intensity magnetic field to cellular food freezing assists supercooling phenomenon, with advantage of enhancing quality. But the development as well as market acceptance of the technology is low because the supercooling phenomenon is not well-understood. Currently, insightful studies on the supercooling phenomenon of magnetic field-assisted freezing and its impacts on quality preservation of fruits and vegetables have been unveiled. The studies revealed that the strong magnetic field assistance to freezing is possible through the exhibition of electron spins and re-ordering of magnetic ions of water molecules contained in cellular foods. However, the results outlined in this study offer comprehensive insights into the supercooling phenomenon of magnetic field-assisted freezing and its impacts on the freezing process and the quality preservation of fruits and vegetables, offering valuable guidance for future developments of strong magnetic field-assisted freezing technology. [ABSTRACT FROM AUTHOR]

Current article presents a numerical modeling of the discharging process within a finned tank using the Galerkin method integrated with an implicit technique. The model dynamically adapts the grid configuration to the position of the solidification front, ensuring precise capture of the unsteady process. To enhance the freezing rate, alumina nanoparticles of various diameters (dp) and concentrations (ϕ) were introduced into the water. The properties of the nanocomposite material were estimated assuming a homogeneous mixture, with conduction considered the primary mechanism of heat transfer. The results demonstrate that increasing the (ϕ) significantly accelerates the solidification, reducing the required time by 41.31%, from 9579.68 to 5621.78 s. The study also reveals a complex relationship between nanoparticle diameter (dp) and freezing time, where initial increases in dp reduce the freezing period by 20%, followed by an increase of 48.38% with further increases in dp. [ABSTRACT FROM AUTHOR]

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Surface water extraction (SWE) from very-high-resolution optical remote sensing images is crucial yet challenging due to the complex spectral variability of water bodies. To address this, we propose Water-Adapter, a novel method that enhances SWE by leveraging the Segment Anything Model (SAM), a large-scale image segmentation framework. Our approach introduces a task-specific input module that utilizes explicit visual prompting by focusing the tunable parameters on the visual content of each image, specifically leveraging features from frozen patch embeddings and low-frequency components. By freezing most of SAM's image encoder parameters and incorporating a few domain-specific trainable adapters, Water-Adapter effectively integrates remote sensing knowledge into SAM, significantly improving segmentation performance with minimal computational overhead. Extensive experiments on the GLH-Water dataset demonstrate that Water-Adapter outperforms state-of-the-art methods in both accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Recently, vision transformer (ViT) based multimodal learning methods have been proposed to improve the robustness of face anti-spoofing (FAS) systems. However, there are still no works to explore the fundamental natures (e.g., modality-aware inputs, suitable multimodal pre-training, and efficient finetuning) in vanilla ViT for multimodal FAS. In this paper, we investigate three key factors (i.e., inputs, pre-training, and finetuning) in ViT for multimodal FAS with RGB, Infrared (IR), and Depth. First, in terms of the ViT inputs, we find that leveraging local feature descriptors (such as histograms of oriented gradients) benefits the ViT on IR modality but not RGB or Depth modalities. Second, in consideration of the task (FAS vs. generic object classification) and modality (multimodal vs. unimodal) gaps, ImageNet pre-trained models might be sub-optimal for the multimodal FAS task. Finally, in observation of the inefficiency on direct finetuning the whole or partial ViT, we design an adaptive multimodal adapter (AMA), which can efficiently aggregate local multimodal features while freezing majority of ViT parameters. To bridge these gaps, we propose the modality-asymmetric masked autoencoder (M 2 A 2 E) for multimodal FAS self-supervised pre-training without costly annotated labels. Compared with the previous modality-symmetric autoencoder, the proposed M 2 A 2 E is able to learn more intrinsic task-aware representation and compatible with modality-agnostic (e.g., unimodal, bimodal, and trimodal) downstream settings. Extensive experiments with both unimodal (RGB, Depth, IR) and multimodal (RGB+Depth, RGB+IR, Depth+IR, RGB+Depth+IR) settings conducted on multimodal FAS benchmarks demonstrate the superior performance of the proposed methods. One highlight is that the proposed method is robust under various missing-modality cases where previous multimodal FAS models suffer serious performance drops. We hope these findings and solutions can facilitate the future research for ViT-based multimodal FAS. [ABSTRACT FROM AUTHOR]

This study investigated the evolution of mass-exchange, physicochemical, mechanical, thermal, and structural properties of meat analog (MA)-based batter-coated parfried food. Wheat and rice flour–based batter systems were used to coat the MA. Parfried (at 180 °C for 60 s) MA were frozen at − 18 °C, − 76 °C, and liquid N2 and stored at − 18 °C for up to 6 months. Parfried MA were finish-fried at 180 °C for 180 s and their attributes were studied. Results reveal that batter formulation and freezing considerably impact the moisture-fat profile as well as textural attributes (hardness, brittleness, crispiness) of finish-fry–coated MA. The color of finish-fry–coated MA is batter formulation–dependent and different than parfried MA. Freezing at − 76 °C slowed quality deterioration of parfried MA in comparison to freezing at − 18 °C. Compared to low-moisture–containing parfried MA, high-moisture–containing coated parfried MA are greatly affected by the freezing process and frozen storage. Storage loss (SL, %) of coated parfried MA increased with the duration of frozen storage, and SL is greatly impacted by batter formulation. Frozen storage duration of parfry-coated MA is negatively correlated with the moisture content of finish-fried MA. Storage duration is positively correlated with fat content and hardness of finish-fried MA. Batter formulation impacted glass-transition temperature (Tg) of parfried MA, that consequently affected their frozen storage quality and finish-frying behavior. Scanning electron microscopy provided mechanistic insights in understanding the impacts of batter formulation and freezing rates on microstructural attributes and consequentially quality evolution of MA-based coated product. [ABSTRACT FROM AUTHOR]

Innate defensive behaviors are essential for species survival. While these behaviors start to develop early in an individual's life, there is still much to be understood about how they evolve with advancing age. Considering that aging is often accompanied by various cognitive and physical declines, we tested the hypothesis that innate fear behaviors and underlying cerebral mechanisms are modified by aging. In our study we investigated this hypothesis by examining how aged mice respond to a looming visual threat compared to their younger counterparts. Our findings indicate that aged mice exhibit a different fear response than young mice when facing this imminent threat. Specifically, unlike young mice, aged mice tend to predominantly display freezing behavior without seeking shelter. Interestingly, this altered behavioral response in aged mice is linked to a distinct pattern of functional brain connectivity compared to young mice. Notably, our data highlights a lack of a consistent brain activation following the fear response in aged mice, suggesting that innate defensive behaviors undergo changes with aging. [ABSTRACT FROM AUTHOR]

In this review, the physicochemical and conformational changes of myofibrillar proteins (MPs) of freeze-induced mince-based aquatic foods were comprehensively summarized in depth. Studies have demonstrated that temperature fluctuation and long-time freezing negatively affect food quality, resulting in texture alteration, drip fluid, flavor degradation, and nutrition loss due to MPs denaturation, aggregation, and oxidation. Attempts have been made in ice-recrystallization inhibition, freezing point depression, and ice shape and growth control for better cryopreservation. Moreover, to further minimize the quality deterioration, cryoprotectants were acknowledged to reduce the denaturation and aggregation of the MPs effectively. Recently, interest in novel functional ingredients, including oligosaccharides, protein hydrolysates, and natural polyphenols demonstrated excellent cryoprotective effects while avoiding health concerns and undesirable flavor caused by traditional sugar-based or phosphates-based cryoprotectants. Therefore, the present review provides a systematic overview of these low molecular weight multifunctional substances with a particular sequence and highlights their underlying mechanism in the inhibition of ice recrystallization the stabilization of MPs. [ABSTRACT FROM AUTHOR]

Since Artificial ground Freezing (AGF) appeared in the 1880s in the mining sector in Europe, it has been used for various construction applications worldwide. In recent years, it has been increasingly popular in urban projects due to its versatility and applicability to complicated site conditions. So far, it has been used to stabilize substrata to nearly 1,000 m below the ground surface, which is considered not possible for many other ground improvement technologies. Due to the growth in field applications, the practice and theories related to AGF have become more mature in the most recent two decades. The improvement in understanding of this topic is a result of lessons that have been learned through numerous projects, as well as a variety of comprehensive studies that have been completed. This paper reviews the existing practice, the recent development on AGF and the challenges of AGF. [ABSTRACT FROM AUTHOR]

The household refrigerator model used for freezing processes in this study was produced in the factory in different energy classes (C, D, and E). Equal amounts of beef (10 × 10 × 2 cm; 2 × 2 × 2 cm) and minced beef (10 × 10 × 2 cm) were placed in refrigerator bags before freezing. The freezing processes were carried out by placing beef samples on the top shelf where the radial fan was located in the freezer compartment of the refrigerators. After the frozen samples were thawed at +4°C, they were cooked in a water bath at 85°C. It was determined that the samples frozen in the refrigerator belonging to the D energy class at −24°C had shorter freezing times and therefore higher freezing rates. It was observed that pH (5.54–5.72) values of samples frozen in the D energy class were higher due to lower weight loss (0.32%–6.80%) values. When their color values were examined, the redness (a∗) values (15.09–17.61) were the highest, while the yellowness (b∗) values (10.31–13.29) were the lowest in these samples. In addition, the hardness (49.00–182.74) and chewiness (16.35–71.80) values of samples frozen in Energy Class D were found to be lower, while their protein denaturation temperatures were higher due to shorter freezing times. Consequently, in this study, the effects of the difference in energy classes of refrigerators on the quality characteristics of beef samples were examined, and the refrigerator belonging to the energy class (D) that gave the best quality properties was found to be the most suitable one for freezing the beef. [ABSTRACT FROM AUTHOR]

When faced with danger, human beings respond with a repertoire of defensive behaviors, including freezing and active avoidance. Previous research has revealed a pattern of physiological responses, characterized by heart rate bradycardia, reduced visual exploration, and heightened sympathetic arousal in reaction to avoidable threats, suggesting a state of attentive immobility in humans. However, the electrocortical underpinnings of these behaviors remain largely unexplored. To investigate the visuocortical components of attentive immobility, we recorded parieto-occipital alpha activity, along with eye movements and autonomic responses, while participants awaited either an avoidable, inevitable, or no threat. To test the robustness and generalizability of our findings, we collected data from a total of 101 participants (76 females, 25 males) at two laboratories. Across sites, we observed an enhanced suppression of parieto-occipital alpha activity during avoidable threats, in contrast to inevitable or no threat trials, particularly toward the end of the trial that prompted avoidance responses. This response pattern coincided with heart rate bradycardia, centralization of gaze, and increased sympathetic arousal. Furthermore, our findings expand on previous research by revealing that the amount of alpha suppression, along with centralization of gaze, and heart rate changes predict the speed of motor responses. Collectively, these findings indicate that when individuals encounter avoidable threats, they enter a state of attentive immobility, which enhances perceptual processing and facilitates action preparation. This state appears to reflect freezing-like behavior in humans. [ABSTRACT FROM AUTHOR]

Fundamental questions in bud dormancy remain, including what temperatures fulfill dormancy requirements (i.e. chill accumulation). Recent studies demonstrate freezing temperatures promote chill accumulation and cold hardiness influences time to budbreak—the phenotype used for dormancy evaluations. Here we evaluated bud cold hardiness and budbreak responses of grapevines (Vitis hybrids) throughout chill accumulation under three treatments: constant (5 °C), fluctuating (−3.5 to 6.5 °C daily), and field conditions (Madison, WI, USA). Chill treatments experiencing lower temperatures promoted greater gains in cold hardiness (field>fluctuating>constant). All treatments decreased observed time to budbreak with increased chill accumulation. However, perceived treatment effectiveness changed when time to budbreak was adjusted to remove cold acclimation effects. Among three classic chill models (North Carolina, Utah, and Dynamic), none was able to correctly describe adjusted time to budbreak responses to chill accumulation. Thus, a new model is proposed that expands the range of chill accumulation temperatures to include freezing temperatures and enhances chill accumulation under fluctuating temperature conditions. Most importantly, our analysis demonstrates that adjustments for uneven acclimation change the perceived effectiveness of chill treatments. Therefore, future work in bud dormancy would benefit from simultaneously evaluating cold hardiness. [ABSTRACT FROM AUTHOR]

Although the recent state-of-the-art systems show almost perfect performance, analysis of speaker embeddings has been lacking thus far. An in-depth analysis of speaker representation will be performed by looking into which features are selected. To this end, various intermediate representations of the trained model are observed using graph attentive feature aggregation, which includes a graph attention layer and graph pooling layer followed by a readout operation. To do so, the TIMIT dataset, which has comparably restricted conditions (e.g., the region and phoneme) is used after pre-training the model on the VoxCeleb dataset and then freezing the weight parameters. Through extensive experiments, there is a consistent trend in speaker representation in that the models learn to exploit sequence and phoneme information despite no supervision in that direction. The results shed light to help understand speaker embedding, which is yet considered to be a black box. [ABSTRACT FROM AUTHOR]

Plants respond to cold stress at multiple levels, including increasing cytosolic calcium (Ca2+) influx and triggering the expression of cold-responsive genes. In this study, we show that the Ca2+-permeable channel CYCLIC NUCLEOTIDE–GATED CHANNEL20 (CNGC20) positively regulates freezing tolerance in Arabidopsis (Arabidopsis thaliana) by mediating cold-induced Ca2+ influx. Moreover, we demonstrate that the leucine-rich repeat receptor-like kinase PLANT PEPTIDE CONTAINING SULFATED TYROSINE1 RECEPTOR (PSY1R) is activated by cold, phosphorylating and enhancing the activity of CNGC20. The psy1r mutant exhibits decreased cold-evoked Ca2+ influx and freezing tolerance. Conversely, COLD-RESPONSIVE PROTEIN KINASE1 (CRPK1), a protein kinase that negatively regulates cold signaling, phosphorylates and facilitates the degradation of CNGC20 under prolonged periods of cold treatment, thereby attenuating freezing tolerance. This study thus identifies PSY1R and CRPK1 kinases that regulate CNGC20 activity and stability, respectively, thereby antagonistically modulating freezing tolerance in plants. Two kinases phosphorylate distinct sites in a Ca2+-permeable channel to regulate its activity and stability, thereby antagonistically modulating freezing tolerance in plants. [ABSTRACT FROM AUTHOR]

Diatoms are among the most important primary producers in alpine and polar freshwaters. Although temperate diatoms are sensitive to freezing, polar diatoms often exhibit more resistance. This is particularly true for members of the (predominantly terrestrial) Pinnularia borealis species complex. However, it remains unclear to what extent this resistance applies to other representatives of the genus. Here, we compare the freezing‐stress tolerance of 11 freshwater, benthic strains representing different species of Pinnularia (including Caloneis) from polar, alpine, and temperate habitats. As vegetative cells, strains were exposed to freezing temperatures of −4, −10, −20, −40, −80, and −196°C. Survival was assessed by light microscopy and photosynthetic measurements. We observed vegetative cells to be sensitive to low freezing temperatures; only "mild" freezing was survived by all tested strains, and most tested strains did not survive treatments ≤−10°C. However, individual strain sensitivities appeared related to their original habitats. For example, polar and alpine strains better withstood "mild" and "moderate" freezing (−4 and −10°C, respectively); although temperate strains were significantly affected by the "mild" freezing treatment, polar and alpine strains were not. The −10°C treatment was survived exclusively by polar strains, and only P. catenaborealis survived all treatments. Interestingly, this species exhibited the lowest survival in the −10°C treatment, potentially implying some metabolic activity even at freezing temperatures. Thus, despite more extensive sampling throughout the genus and finer temperature scaling compared to previous studies, the remarkable freezing‐stress tolerance of the P. borealis species complex remains unique within the genus. [ABSTRACT FROM AUTHOR]

Context: We explore the influence of strongly hydrophilic confinement on various properties of water, such as density, enthalpy, potential energy, radial distribution function, entropy, specific heat capacity, structural dynamics, and transition temperatures (freezing and melting temperatures), using monatomic water (mW) model. The properties of water are found to be dependent on confinement and the wall-fluid surface interaction. Hysteresis loops are observed for density, enthalpy, potential energy, and entropy around the transition temperatures, while the size of hysteresis loops varies with confinement and surface interaction. In smaller pore sizes (H ≤ 20), the solid phase displays a higher density compared to the liquid phase, which is unconventional behavior compared to bulk water systems due to the pronounced hydrophilic properties of the confinement surface. Specific heat capacity exhibits more oscillations in the confined system compared to bulk water, stemming from uneven enthalpy differences across equal temperature intervals. During phase transformation in both heating and quenching processes, there is an abrupt change observed in specific heat capacity. Confinement exerts a notable impact on entropy in the solid phase, but its influence is negligible in the liquid phase. At lower pore sizes (H < 25 Å), there is more fluctuation in freezing temperature for all wall-fluid interactions, which diminishes beyond pore sizes of H > 25 Å. Similarly, more oscillatory behavior is observed in melting temperatures at lower pore sizes (H < 40 Å), which diminishes at higher pore sizes (H > 40 Å). During the quenching process, a sudden jump in the in-plane orientational and tetrahedral order parameters indicates the formation of an ordered phase, specifically a diamond crystalline structure. The percentages of different crystalline structures (cubic diamond, hexagonal diamond, and 2D hexagonal) vary with both the confinement size and the wall-fluid interaction strength. Methods: Cooling and heating simulations are conducted with the mW water model using LAMMPS for different nanoscale confinement separation sizes ranging from 8.5 to 70 Å within the temperature range of 100–350 K. The water is modeled using two-body and three-body interaction potential (Stillinger–Weber potential) and the confinement is introduced using LJ 9–3 water-wall interaction potential. Entropy is calculated using RDF data obtained from the simulation experiments for each temperature point with increments or decrements of 2.5 K. The transition temperatures are estimated using the specific heat capacity analysis. [ABSTRACT FROM AUTHOR]

The bright band (BB) is an important symbol of the ice–water transition zone in stratiform precipitation, and the presence or absence of BB will lead to different microphysical processes. In this paper, the characteristics of BB and precipitation characteristics with and without BB in summer at Tibetan Plateau (TP) as well as Central-eastern China (CEC) are analyzed by using Global Precipitation Measurement (GPM) and the fifth generation ECMWF atmospheric reanalysis of the global climates (ERA5) datasets. The results show the freezing level height and BB height in TP are 0.5 km higher than those in CEC. With the increase in rain rate, the BB height decreases in TP but increases in CEC. The BB width becomes wider with the increase in maximum radar reflectivity. Secondly, the maximum reflectivity factor and particle diameter of stratiform precipitation with BB appear at 5 km, while the maximum reflectivity factor of stratiform precipitation without BB and convective precipitation appear near the ground. The particle diameter first decreases and then increases from the cloud top to the ground. Thirdly, the land surface temperature of convective precipitation is about 2.5 °C higher than stratiform precipitation with BB, indicating higher land surface temperatures are more likely to trigger convection. Lastly, BB can lead to a decrease in brightness temperature and an increase in polarized difference at 89 GHZ and 166 GHZ in CEC, likely due to the increasing ice particles in stratiform precipitation with BB. [ABSTRACT FROM AUTHOR]

The present study compares two protocols for the cryopreservation of chicken semen. Both protocols had an initial low cooling rate in the first step, followed by higher cooling rates around ice nucleation (Protocol 1) or following the dissipation of the latent heat of fusion (Protocol 2) in the second step. Semen ejaculates obtained from 12 roosters were diluted with Rootex with 6% dimethylformamide and frozen following either Protocol 1 (from +5°C to −10°C at 5°C/min and from −10°C to −130°C at 60°C/min) or Protocol 2 (from +5°C to −35°C at 7°C/min and from −35°C to −140°C at 60°C/min). Compared with fresh semen, following both protocols, cryopreservation resulted in reduced post‐thaw sperm quality (p <.001). Post‐thaw percentage of sperm with an intact plasma membrane was greater using Protocol 2 than Protocol 1 (p <.05). The results suggest that high cooling rates around the time of ice nucleation are not recommendable. [ABSTRACT FROM AUTHOR]

Compared with traditional methods, cavitation-based processing technology has received extensive attention for its low energy consumption and high processing efficiency. The cavitation phenomenon releases high energy due to the generation and collapse of bubbles, which improves the efficiency of various food processing. This review details the cavitation mechanism of ultrasonic cavitation (UC) and hydrodynamic cavitation (HC), factors affecting cavitation, the application of cavitation technology in food processing, and the application of cavitation technology in the extraction of various natural ingredients. The safety and nutrition of food processed by cavitation technology and future research directions are also discussed. The mechanism of UC refers to longitudinal displacement of the particles of the medium induced by ultrasonic waves causing a series of alternating compression and rarefaction of particles, whereas HC occurs when liquid enters a narrow section and undergoes large pressure differentials, both of which can trigger the generation, growth, and collapse of microbubbles. Cavitation could be applied in microbial inactivation, and drying and freezing processing. In addition, cavitation bubbles can have mechanical and thermal effects on plant cells. In general, cavitation technology is a new sustainable, green, and innovative technology with broad application prospects and capabilities. [ABSTRACT FROM AUTHOR]

The wide spread adoption of heat pipes in automotive and aviation application is hampered by the fact that they require protection against frost damage caused by the repetitive exposure to subzero temperatures. Here, we present heat pipe with ethylene glycol and water as working fluid that can prevent damage to the copper container on exposure to cyclic freezing and thaw. In this research, different mass concentrations of water and ethylene glycol have been tested for freeze protection of heat pipes. Experimental investigations have shown that 3.5% by mass concentration of ethylene glycol in water is able to sustain the cyclic freezing and avoid any damage to the copper pipe. In this research, the freezing and heating cycle is set to operate between -40 °C and 90 °C. Heat pipes used for testing in this research were 6 mm in diameter and 150 mm long with copper fiber spiral wick. Thermal performance tests were carried out on these heat pipes with charging ratio of working fluid varying between 10% to 30% by volume. It is observed that the thermal resistance of heat pipe with working fluid charging ratio in range of 10% to 25% by volume varies from 0.6 °C/W to 0.2 °C/W for the rate of heat transfer of 10 W-50 W. While the charging ratios beyond 25% have shown the higher thermal resistance in the range of 0.8 to 1.0 °C/W for similar rate of heat transfer. All the samples were subjected to 150 freezing and thaw cycles and did not show any signs of frost damage. Accelerated life tests were performed on these heat pipes for up to 500 h and did not presented any signs of degradation in their thermal performance. [ABSTRACT FROM AUTHOR]

In this study, a cabin design was made for fast freezing in household refrigerators using different fan types (radial fan velocity of 1100, 1500 and 1900 rpm) and axial (1350 rpm) and the effects on the quality characteristics of beef were examined. Before the freezing process, the beef (Semitendinosus) was sized at 10 × 10 × 2 cm as a single fillet; 2 × 2 × 2 cm as the cubed sample and the minced beef was prepared by the butcher from the same meat and shaped with the dimensions of 10 × 10 × 2 cm. It was seen that when the fan velocity was 1900 rpm during the freezing process, the weight (0.39–11.61 %) and cooking loss (26.69–44.66 %) values of the beef samples decreased. A decrease was observed in the TBARS values (0.34–0.87) of the sample as the radial fan velocity increased in radial fan. When the total color change values (3.96–7.59) of all beef samples were examined, it was seen that the least color change was achieved with the axial fan before and after cooking. When the textural properties of the meat were examined before and after cooking, it was observed that the hardness decreased as the radial fan velocity increased, and the lowest hardness value was obtained from freezing with the axial fan. In addition, porosity values decreased and protein denaturation temperatures increased due to the formation of smaller ice crystals with the axial fan. As a result, it has been observed that fan type and velocity have significant effects on accelerating the freezing process and preserving the quality of beef samples. [ABSTRACT FROM AUTHOR]

Late spring frost is the most hazardous abiotic stress affecting the survival of sugar beet seedlings. Therefore, it is very important to identify frost-tolerant cultivars during the early seedling development stage. In the study, the physiological and morphological responses of ten sugar beet cultivars (Ernestina, Isabella, Orthega, Serenada, Kuno, Taurus, Tuna, Mohican, Rodeo, and Smılodon) to frost stress at different growth stages (V1.1, V2.1, and V3.1) were evaluated. Seedlings were exposed to − 3 °C for 2 h at all stages. Percent damage (%), leaf chlorophyll content (SPAD), leaf surface temperature (°C), electrolyte leakage (%), leaf relative water content (%), and turgidity loss (%) were examined. The results showed that higher damage percentages were observed in earlier growth stages of sugar beet, with recorded values of 29.7% in V1.1, 15.4% in V2.1, and 3.6% in V3.1. A great genotypic variation was observed among the cultivars; electrolyte leakage increased from 15.6% in control to 52.6% in frost stress, and higher electrolyte leakage was obtained from frost-stressed plants. The relative water content of leaves increased only at stage V2.1, although frost decreased turgor loss. Sugar beet showed sensitivity to frost in earlier seedling growth stages, but their tolerance levels increased in later growth stages. The study revealed that electrolyte leakage is a reliable indicator for identifying sugar beet cultivars that exhibit tolerance to frost stress during early development. [ABSTRACT FROM AUTHOR]

Biological drug substance (DS) is often frozen to enhance storage stability, prolong shelf life, and increase flexibility during manufacturing. However, the freezing and thawing (F/T) of bulk DS at the manufacturing scale can impact product quality as a result of various critical conditions, including cryo-concentration during freezing, which are influenced, among other things, by product-independent process parameters (e.g., container type, fill level, F/T equipment, and protocols). In this article, we report the optimization of two major methodologies to study product-independent process parameters in DS bottles at the manufacturing scale, namely the recording of temperature profiles and liquid sampling after thawing to quantify the concentration gradients in the solution. We report experimentally justified measuring positions for temperature recordings, especially for the selection of the last point to freeze position, and highlight the implementation of camera-assisted inspection to determine the last point to thaw and the actual thawing time. In particular, we provide, for the first time, a detailed description of the technical implementation of these two measuring set-ups. Based on the reported case studies, we recommend choosing relevant measuring positions as a result of initial equipment characterization, resulting in a resource-conscious study set-up. [ABSTRACT FROM AUTHOR]

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This study explored the effects of three different freezing and thawing methods on the behavior of quality parameters in raw beef meat. Also, the usage of inulin as a cryoprotectant was investigated. The beef was subjected to freezing using three distinct. Methods Static freezing (I), air blast freezing (II), and individual quick freezing (III). After the freezing process, the samples were subjected to a thawing procedure in the microwave, refrigerator (4 °C), and room temperature (25 °C) conditions. Dry matter content, pH, color, hardness, chewiness, thaw loss, ion leakage, cooking loss, and lipid oxidation values were measured at the beginning of the storage and monthly intervals during 180-day storage period. The use of inulin significantly affected all the properties except for the textural properties. Rapid freezing methods have reduced the thaw loss, ion leakage and cooking loss values while thawing under refrigeration conditions was effective for the preservation of overall quality. The use of inulin together with rapid freezing methods enhanced the freezing tolerance of beef samples effectively during the 6-month storage period. [ABSTRACT FROM AUTHOR]

ABSTRACTStrawberries intended for processing are usually frozen to withstand storage and distribution. However, freezing and thawing can cause the degradation of bioactive compounds. The aim of this study was to determine the optimal conditions for frozen storage and thawing to minimize any loss of nutrients prior processing. Different freezing treatments (−20°C, shock-freezing with liquid nitrogen, −80 °C) up to 6 months of storage and thawing treatments (4°C, room temperature, 37°C, microwave) were compared based on the content of organic acids, sugars, and phenolic compounds as well as the activity of peroxidase and polyphenol oxidase. During frozen storage at −20°C over 6 months, the sucrose content decreased by 59%, but only a 17% loss of ascorbic acid was observed, and no significant loss of anthocyanins was detected. However, more significant changes in composition were detected after thawing. When thawed at 4°C for 24 h, ascorbic acid content decreased by 32%, anthocyanin content by 30%, and sucrose content by 66%. Based on our study, the frozen storage caused smaller changes in the fruit’s composition than thawing. From the thawing procedures, the microwave thawing showed minimal changes in the composition of strawberries.

In 2021–2024, cryopreservation experiments focused on dormant shoots of pome and stone fruit trees were conducted. The classic freezing protocol, which uses single-nodal segments, was modified towards segments with several nods. In the case of apple and pear trees, we noticed striking variance in the viability among different (or even the same) varieties in different years. Depending on the variety and season, initial drying to 40 and 30% proved effective for apple buds. For pears, it was 40 and 35% in 2023 for ‘Lucasova’. Of the cryopreserved stone fruit trees, only the plum ‘Stanley’ showed demonstrable, albeit low viability of the buds. Seasonal fluctuations are likely to be caused by extreme temperatures during recent winters. In 2025, the results of the budding from the summer of 2024 will be known. However, the course of the experiment in this season, when we focused on the role of the shoot collection date, was again largely affected by the extraordinarily warm weather.

Stress is an adaptive response crucial for survival. However, chronic stress can lead to maladaptive behaviors and health issues. Prolonged stress reduces the flexibility of defensive coping behaviors. Previous studies have shown that the medial prefrontal cortex (mPFC) and the nucleus accumbens (NAc) play critical roles in maintaining active avoidance instead of freezing behaviors in face of threats. This study aimed to investigate whether chronic stress altered the prelimbic cortex, infralimbic cortex, NAc core and the NAc shell neuronal activation levels and the defensive coping in male rats in face of danger, and we hypothesized that the activation levels of these two brain regions would decrease and the animals would spend more time in freezing. The animals underwent a chronic restraint stress procedure (2 h/day) for consecutive 14 days. Using a cued lever-pressing shock avoidance task, we assessed the avoidance coping and the neuronal activities in the mPFC and the NAc. Our results showed that compared to nonstressed controls, animals that underwent chronic restraint stress were slower in gaining body weight and developed despair-like behaviors in the forced swim test. However, contrary to our hypothesis, chronic restraint stress did not alter active avoidance coping or neuronal activation levels of the mPFC and the NAc.

Objective. The purpose of the study is to develop the design of a thermoelectric installation for lifting objects from shallow reservoirs using the freezing method, as well as its calculation, analysis of parameters and electrical and thermophysical characteristics. Method. The research is based on the use of methods of thermodynamic analysis, full-scale and computational modeling of cryogenic equipment in order to find optimal solutions for the reliability and service life of low-temperature installations. Result. The installation includes a waterproof probe, on the end surface of which, facing the bottom of the reservoir, thermoelectric modules are installed, heat is removed from the hot junctions of which by means of a heat removal system made in the form of an all-metal heat pipe or in the form of a thermal thermosiphon. The connection between the object lifted from the reservoir and the thermoelectric installation is carried out through a cold wall by freezing. The thermoelectric installation was calculated and its parameters were determined. Graphs were constructed and dependencies were obtained describing the main characteristics of TEMs included in the thermoelectric installation. The graphs are presented at a temperature of the hot junctions of the TEM of 300 K and the achievement of such values of the thickness of frozen water ice on the cold wall of the technical device that would allow lifting objects from a reservoir up to 4 m deep. Conclusion. The installation parameters have been determined: the number of TEMs of the DRIFT-1.2 type is 8, the operating power range of a single TEM of the DRIFT-1.2 type is from 14 to 40 W with an average temperature difference between the junctions of 45 K, the supply current is from 3.8 to 7 .6 A with power consumption from 50 to 200 W, coefficient of performance - from 0.1 to 0.45, minimum temperature of the cold wall of the TU - 248 K, a domestically produced thermal thermosyphon is used as a heat removal system from the hot junctions of the TEM.

Polymeric spherulites are typically formed by melt crystallization: spherulitic growth in solution is rare and requires complex polymers and dilute solutions. Here, we report the mild and unique formation of luminescent spherulites at room temperature via the simple molecule benzene-1,4-dithiol (BDT). Specifically, BDT polymerized into oligomers (PBDT) via disulfide bonds and assembled into uniform supramolecular nanoparticles in aqueous buffer; these nanoparticles were then dissolved back into PBDT in a good solvent (i.e., dimethylformamide) and underwent chain elongation to form spherulites (rPBDT) in 10 min. The spherulite geometry was modulated by changing the PBDT concentration and reaction time. Due to the step-growth polymerization and reorganization of PBDT, these spherulites not only exhibited robust structure but also showed broad clusterization-triggered emission. The biocompatibility and efficient cellular uptake of the spherulites further underscore their value as traceable drug carriers. This system provides a new pathway for designing versatile superstructures with value for hierarchical assembly of small molecules into a complicated biological system.

Sweet corn is frequently consumed in the US and contains carbohydrates as major macronutrients. This study examined the effects of blanching, freezing, and canning on carbohydrates in sweet corn. Fresh bi-color sweet corn was picked in the field and processed immediately into frozen and canned samples. Simple sugars, starch, and dietary fiber (DF) (including total DF (TDF), insoluble DF (IDF) and two fractions of soluble DF (SDF)) were measured according to the AOAC methods. Additional glycomic analysis including oligosaccharides, monosaccharide composition of total polysaccharides (MCTP) and glycosidic linkage of total polysaccharides (GLTP) were analyzed using UHPLC-MS. Sucrose is the major simple sugar, and IDF is the main contributor to TDF. Sucrose and total simple sugar concentrations were not altered after blanching or freezing but were significantly reduced in canned samples. Kestose was the only oligosaccharide identified in sweet corn and decreased in all heat-treated or frozen samples. Starch content decreased in frozen samples but increased in canned samples. While two SDF fractions did not differ across all samples, blanching, freezing and canning resulted in increases in TDF and IDF. Six monosaccharides were identified as major building blocks of the total polysaccharides from MCTP analysis. Glucose and total monosaccharide concentrations increased in two canned samples. GLTP was also profoundly altered by different food processing methods. This study provided insights into the changes in the content and quality of carbohydrates in sweet corn after food processing. The data are important for accurate assessment of the carbohydrate intake from different sweet corn products.

Under threats, individuals exhibit freezing behavior and prepare for active coping. The ability to flexibly shift between freezing and active coping increases survival chances in animals and decreases susceptibility to mental disorders among human beings. For example, patients with psychiatric disorders, such as obsessive-compulsive disorder and posttraumatic stress disorder, often show maladaptive coping behaviors. The orbitofrontal cortex (OFC) is a critical hub to process higher cognitive functions, sensory inputs, reward learning, and decision-making. It also regulates negative emotions and its aberrant activation level often correlates with numerous mental disorders. The rodent OFC comprises different subdivisions with varying connections to cortical and subcortical regions. Among these subdivisions, the medial orbital area (MO) and the lateral orbital area (LO) have distinct functions in the regulation of fear. Here, we updated the existing rodent literature studying the function of the OFC, with a particular focus on the MO and the LO in different coping strategies of animals. By examining the role of the OFC in the mediation of defensive coping strategies, we aim to deepen the understanding of its functional importance on mental health.

Abstract. Shrimp is one of the most preferred seafood for consumption. The high water content and nutrients place shrimp in the category of perishable fast spoiling foods. In order to avoid deterioration of their quality, it is necessary to freeze and store them at low temperatures. Fluctuations in temperature can cause thawing and refreezing with recrystallization. In frozen products, the amount and size of ice crystals play a major role in the quality of these products. Despite the wide application of freezing, various histological, physicochemical, microbiological, enzymes and pH changes occur with varying degrees of manifestation. The objective of the review was to discuss the effect of freezing on the quality of shrimp used for human consumption.

Objective The Hu sheep is a renowned breed known for its high reproductive rate. It is in estrus all year round, and its breeding population is gradually expanding. However, the current techniques for cryopreserving semen have limited effectiveness, which hinders the continuous development of this species. The purpose of this study is to explore the effects of different penetrating cryoprotectants (CPAs) and egg yolk (EY) concentrations on the cryopreservation of Hu ram semen to determine the most effective combination. Methods In this study, the effects of glycerol (GLY), ethylene glycol (EG), dimethylacetamide, dimethyl sulfoxide, different proportions of GLY and EG, EY on sperm quality after thawing were investigated by detecting sperm total motility (TM), progressive motility (PM), straight-line velocity, curvilinear velocity, average path velocity, amplitude of lateral head displacement, wobble movement coefficient, average motion degree, functional integrity (plasma membrane integrity, acrosome integrity) and reactive oxygen species (ROS) level. Results When GLY and EG were added together, compared to other concentration groups, 6% GLY significantly (p

Abstract Key message Winter reddening of young Douglas-fir (Pseudotsuga menziesii Mirb. Franco), triggered by large thermal fluctuations in late winter, is a critical problem for European forestry. A literature review identified certain climatic conditions that are characteristic of ‘reddening’ years, including warm daily temperatures, high daily temperature amplitude, low relative humidity, moderate wind speeds, as well as the occurrence of freeze-thaw cycles with cold night temperatures. By describing the triggering environmental and stand factors, we propose three hypotheses for the physiological processes leading to winter reddening, namely (i) hydraulic failure due to winter drought stress, (ii) photo-oxidative stress in shade-acclimated trees, and (iii) early cold deacclimation during warm periods. i) Low soil temperature, by reducing root water uptake, combined with anticyclonic conditions, by increasing water losses, can induce hydraulic failure in the xylem. Hydraulic failure may be further accelerated by night frosts. ii) Winter reddening can occur when low temperature and high irradiance coincide, disrupting photostasis. Overwhelming of winter photo-protection may lead to photodamage and subsequent reddening. iii) Warm periods, by inducing cold deacclimation, make trees susceptible to frost damage. Finally, the three processes may interact under atypical anticyclonic conditions in late winter (e.g. cold or dry soils, warm days, high irradiance and/or freezing nights). Indeed, trees under water stress would develop a higher sensitivity to freezing night and photooxidative stress. We therefore proposed mitigation actions to avoid exposing trees to stressful conditions based on e.g. stand characteristics, understorey vegetation and planting.

Introduction: To assist save endangered species from extinction and to aid in their care, it is crucial to sustaining their reproductive capacity. The fetus's life and growth processes begin at conception and proceed in accordance with a biological clock's timing. With today's understanding through cryobiology, observing scientific ethics problems and interfering with the clock's operation by stopping its biological time is possible. Practically, it is accomplished by storing the cell at -196 °C, or the temperature of liquid nitrogen, where all metabolic activity ceases. Since 200 years ago, germ cell preservation has been a common practice. Since then, there have been many improvements, particularly for at-risk women. Since then, significant progress has been achieved, and several freezing techniques are being used to preserve ovarian tissue, follicles, and oocytes in women who are at risk of infertility. Different approaches have different levels of success. Among preservation techniques, vitrification performs better and is used more frequently. The cellular configuration of the mammalian oocyte is intricate. This cell's constituent parts are particularly sensitive to osmosis and variations in temperature. For instance, the alterations to the cell membrane that occur during maturation, in vitro fertilization, and the differential between the permeability of water and cryoprotectants can all be mentioned. Oocyte freezing results in a variety of impairments, including a reduction in the quality and viability of cells after thawing. Conclusion:Recent studies are looking for ways to enhance freezing procedures and raise the caliber of frozen oocytes. The favorable or negative effects of freezing on the oocyte and its potential, or embryo development, are the subject of this review article.

The important component in the activities of the collection of starter microorganisms is the preservation of the pool of the strains valuable for industrial production. Lyophilization (also known as freeze drying) is a widely used method for the long-term storage of the collection cultures. The critical parameter of the process of lyophilization is the pre-freezing temperature. This article brings forward the results of researches of the rate of survival of lactococcus strain cultures during their lyophilization with pre-freezing at the temperatures of minus 20 °C, minus 30 °C and minus 55 °C. Reconstituted 10% skim milk was used as the medium for strain culturing and lyophilization. Different reactions were detected among the microorganisms of Lactococcus lactis subsp. lactis, Lactococcus cremoris and Lactococcus lactis subsp. lactis biovar. diacetylactis for their freezing and lyophilization under the tested conditions. The highest rate of survival of lactococcus strains was observed at the freezing temperature of minus 20 °C. The most resistant cultures appeared to be Lactococcus lactis subsp. lactis biovar. diacetylactis — their rate of survival after lyophilization at minus 20 °C amounted to 42.6-57.9%. The lowest survival rate was recorded for Lactococcus cremoris in all freezing modes (from 3.1 to 15.7%). Lyophilization of lactococcus collection cultures ensures high survival rate of the cells.

Objective. The purpose of the study is to develop the design of a thermoelectric device for fastening parts by freezing during machining, and to analyze its parameters and characteristics.Method. The design of a thermoelectric device for fastening parts using the freezing method during their machining is described. The device includes a high-current fuel cell, made on the basis of layered thermoelements with improved thermomechanical characteristics. The fuel cell is interfaced with a heat-equalizing ceramic plate on the side of the cold junctions, and on the side of the hot junctions, through a similar ceramic plate, it is in contact with the heat release system.Result. To ensure the required operating mode of the device, a layered thermoelectric battery developed at the Research Institute of Semiconductor Thermoelectric Devices and Devices can be used in its composition. T.A. Ismailov”, Dagestan State Technical University.Conclusion. The operating power range of the used fuel cell is in the range of 20-50 W with an average temperature difference between the junctions of 50 K, the supply current is 50-80 A with a power consumption of 50-160 W. The refrigeration coefficient varies from 0.1 to 0.45.

Introduction of non-native species is an important cause of biodiversity decline in rivers. Separated by mountains and salt water, the freshwater fish fauna in Italy has experienced a natural isolation from fish in continental Europe. As a consequence, several Italian fish species have diverged from their European sister species, likely with unique adaptations to the local environment. Relatedly, the region is also susceptible to the invasion of non-native fish, and today almost half the fish species present are of non-native origin. Several of these non-native species have Italian congeners susceptible to competition and hybridizations, and, in the long run, displacements and extinctions. One such example is the Italian gudgeon (Gobio benacensis) and its European congener European gudgeon (Gobio gobio). During the last few decades the European gudgeon was introduced in Italian waters and has since spread rapidly, causing progressive declines in the Italian species. As for several other similar species pairs, little is known about potential differences in ecology and behavior. Here we study differences between Italian and European gudgeons in a controlled laboratory environment, using a combined open field and provoked escape response test, as well as tracking their sympatric survival over time in the hatchery. The smaller Italian gudgeon displayed a lower maximum swimming speed compared to the larger European gudgeon. The Italian gudgeon also experienced substantially higher sympatric mortality, resulting in only European gudgeon surviving to the end of the experiment. Contrary to expectations, no difference was seen in boldness and the Italian gudgeon displayed a higher movement activity, moving a larger distance in an open field test, compared to its European sister species. The reported differences could play a role in the replacement process, and may also have impacts on the surrounding ecosystem, and the prey and predators that have coevolved with the Italian species.