Search Results (426)

The mechanical properties of moraine soil in cold regions are significantly influenced by freeze–thaw cycles (FTCs). However, current understanding of the quantitative characteristics of its shear behavior under the coupled effect of FTCs and confining pressure is still insufficient. To address this, a series of triaxial unconsolidated-undrained shear tests were conducted on saturated moraine soil, with different numbers of FTCs (N = 0, 1, 4, 8, 10, 12, 15, 20) and various confining pressures (σ₃ = 100, 200, 300, 400 kPa). The experimental results reveal that: (1) With an increase in the number of FTCs, the stress–strain curves gradually change from strain-softening to strain-hardening types. Correspondingly, the pore water pressure development shifts gradually from a peak-decay pattern to a growth-stabilization pattern. The peak pore water pressure rises linearly with increasing confining pressure, whereas it decays linearly with an increasing number of FTCs. (2) Both the secant modulus E₅₀ and the shear strength increase with higher confining pressure and decrease with more FTCs. Confining pressure exerts a significant inhibitory and compensatory effect on freeze–thaw-induced damage, markedly reducing the deterioration rate under high confining pressure. (3) Quantitative prediction models for E₅₀ and q_max were established, effectively capturing the coupled effect of confining pressure and FTCs. It can be inferred that confining pressure mitigates structural damage by compressing frost-induced cracks and enhancing interparticle contacts, while FTCs exacerbate the degradation of soil mechanical properties because of ice crystal expansion or contraction and weakening of cementation. This study quantifies the coupled effect of confining pressure and FTCs, and the proposed prediction model provides a useful reference or preliminary estimation for relevant geotechnical engineering designs. Full article

Class III aminotransferases represent a structurally and functionally unique subgroup. However, the contribution of specific loop elements to their active-site architecture and cofactor-dependent structural transitions remain underexplored. We elucidated the structural framework underlying the catalytic function of class III fold Pyridoxal 5′-phosphate-dependent aminotransferase from the Antarctic bacterium Hymenobacter sp. PAMC 26554 (HyAT), and report its crystal structure at 2.31 Å resolution. The structure revealed a canonical class III fold organized as a functional homotetramer. Structural analysis identified a proline-containing motif (P-x-P) within the α10-α11 loop, which induces intrinsic disorder at the active-site entrance in the apo-form and revealed that a cooperative disorder-to-order transition is requisite for active-site assembly upon cofactor binding. We propose that this flexible loop region may be involved in modulating substrate access. Notably, this proline motif was conserved in homologs from Hyperthermophiles, despite the cold-adapted nature of HyAT. This convergence implies a common evolutionary strategy where the geometric constraints of proline are exploited to decouple local active-site dynamics from global scaffold stability, thereby addressing the stability–activity trade-off across diverse thermal environments. Our findings provide new molecular insights into the structural dynamics of class III aminotransferases and highlight evolutionary strategies for tuning enzyme flexibility in extreme environments. Full article

Orientation rotation in grain-boundary regions plays a critical role in controlling the crystallographic texture of metallic materials. In this study, the ideal λ texture ({001}<uv0>) in non-oriented silicon steel is chosen as the target orientation. The oriented stability in grain-boundary regions during cold rolling is systematically investigated by combining crystal plasticity simulations and quasi in situ electron backscatter diffraction (EBSD) experiments. Oriented stability is defined as the rate of change in the misorientation angle between an arbitrary orientation and the target orientation, thereby quantifying the rotational tendency relative to the target in grain-boundary regions. The results reveal that the oriented stability in grain-boundary regions is highly sensitive to both the initial and neighboring orientations. For initial orientations near the critical boundary separating convergence and divergence zones, the oriented stability is highly susceptible to neighboring orientations, with some neighboring orientations even reversing the rotation direction. In contrast, when the initial orientation is far from this critical boundary, the influence of neighboring orientations becomes weaker. Furthermore, the concept of contributed oriented stability is introduced to statistically evaluate the effect of different neighboring texture components in polycrystals. This work elucidates the underlying mechanism of orientation rotation in grain-boundary regions, and provides a new theoretical framework and a quantitative strategy for optimizing favorable textures. Full article

Organic–inorganic hybrid crystalline materials formed in multicomponent aqueous systems are of interest because their phase behavior and physicochemical properties can be controlled by composition and crystallization conditions. In this study, the phase equilibria and crystallization behavior of the ternary aqueous Ca(ClO₃)₂·2CO(NH₂)₂–CH₂ClCOOH·(C₂H₄OH)₃N–H₂O system were investigated over the temperature range of −24 to 60 °C using the visual-polythermal method. Experimental data obtained for the two boundary binary subsystems and eight internal sections were used to construct the polythermal phase diagram. The diagram revealed distinct crystallization fields corresponding to ice, Ca(ClO₃)₂·2CO(NH₂)₂·2H₂O, CH₂ClCOOH·(C₂H₄OH)₃N, and a separate crystallization region associated with a previously unreported crystalline phase with the proposed composition ClCH₂COOH·Ca(ClO₃)₂·(C₂H₄OH)₃N. The solid phase was isolated from its crystallization region, washed with cold distilled water, dried to constant mass, and characterized by complementary Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), thermogravimetric analysis, derivative thermogravimetry, and differential scanning calorimetry (TG–DTG–DSC), and powder X-ray diffraction (PXRD). The experimentally determined Ca²⁺ and ClO₃⁻ contents were reasonably consistent with the proposed composition, while FT-IR spectroscopy revealed characteristic chlorate vibrations and changes in the vibrational environment of the organic component. SEM showed predominantly prismatic and plate-like crystalline morphologies, and EDS confirmed the presence of Ca, Cl, O, C, and N. Thermal analysis demonstrated multistage decomposition, with comparatively good thermal stability below approximately 150 °C. PXRD revealed a diffraction fingerprint distinct from those of the starting components and the corresponding physical mixture. Preliminary indexing of 19 principal reflections was consistent with a tetragonal candidate lattice with a = b = 7.7411(5) Å, c = 24.7182(10) Å, V = 1481.2(5) ų, and M₂₀ ≈ 23.0. The crystallographic analysis is considered preliminary because the diffraction profile was reconstructed from the available pattern and was not subjected to complete structure refinement. Overall, the combined phase-equilibrium, compositional, spectroscopic, morphological, thermal, and diffraction data support the isolation of a distinct organic–inorganic crystalline phase with the proposed composition. Full article

Frozen seafood plays an important role in the global food supply, but maintaining its quality during frozen storage and cold-chain distribution remains a significant challenge. Although freezing effectively slows microbial growth and enzymatic activity, it cannot completely prevent quality deterioration. During frozen storage, seafood undergoes a series of interconnected physicochemical changes, including ice crystal growth, protein denaturation and oxidation, lipid oxidation, water redistribution, and texture deterioration. These changes gradually reduce sensory quality, nutritional value, and overall commercial acceptability. Conventional quality assessment methods, including destructive laboratory analyses and sensory evaluation, are still widely used. However, they are often labor-intensive, time-consuming, and unsuitable for rapid or real-time monitoring in modern cold-chain systems. As a result, increasing attention has been given to non-destructive sensing technologies that can evaluate seafood quality quickly and objectively. This review summarizes the major mechanisms responsible for quality deterioration in frozen seafood, together with recent advances in sensing technologies used to monitor these changes. The sensing approaches discussed include near-infrared (NIR) and Raman spectroscopy, hyperspectral and fluorescence imaging, low-field nuclear magnetic resonance (LF-NMR), electronic nose (E-nose), electronic tongue (E-tongue), colorimetric sensor arrays (CSAs), and biosensors. This review also discusses the growing role of artificial intelligence in frozen seafood quality assessment, including chemometrics, machine learning, deep learning, and multi-sensor data fusion. Particular attention is given to their applications in quality prediction, industrial implementation, and decision support. Finally, current challenges and future research needs are highlighted, with emphasis on the development of interpretable, transferable, and real-time monitoring systems that can support more reliable quality assurance throughout the frozen seafood supply chain. Full article

Freeze desalination (FD) is being reconsidered as a low-temperature desalination route because it separates water through ice formation rather than evaporation or membrane pressure. This review examines FD from the perspective of sustainable water–energy systems, with emphasis on applications where conventional desalination may face technical or energy limitations. Unlike general reviews focused mainly on freezing principles, this work connects crystallization mechanisms, experimental performance, energy integration, and scale-up barriers. The literature analyzed, consisting primarily of studies published between 2015 and 2026, was grouped into four areas: modeling and simulation, experimental and pilot-scale validation, technological integration, and energy–economic assessment. Recent progress has been reported in eutectic freeze crystallization, vacuum-assisted ice–brine separation, ice morphology control, LNG cold recovery, solar-assisted FD, and hybrid systems that combine desalination with cooling or energy recovery. Reported performance varies widely. Reported SEC varies by more than an order of magnitude: values near 3 kWh/m³ occur mainly under favorable integration or external-cold assumptions, whereas conventionally refrigerated laboratory and pilot systems can require substantially more energy. This difference shows that FD performance depends strongly on crystallizer design, feedwater composition, separation strategy, and cold-energy recovery. FD should not be viewed as a direct replacement for RO, MED, or MSF. Its strongest potential is in hypersaline brine treatment, LNG terminals, cold regions, off-grid systems, island communities, and decentralized water production coupled with renewable or waste-cold sources. Full article

The increasing demand for sustainable materials has accelerated the development of biodegradable polymer composites with enhanced multifunctional performance for engineering, packaging, and biomedical applications. In this study, poly(lactic acid) (PLA)/polyhydroxyalkanoate (PHA) biocomposites reinforced with microcrystalline cellulose (MCC) and a compatibilizer were fabricated by melt blending followed by compression molding. Fourier-transform infrared spectroscopy confirmed enhanced hydrogen-bonding interactions between MCC and the PLA/PHA matrix, indicating improved interfacial compatibility. X-ray diffraction and Differential scanning calorimetry revealed that MCC acted as an significant heterogeneous nucleating agent, increasing the crystallinity from 28.6% for the neat PLA/PHA blend (S0) to 40.1% while reducing the cold crystallization temperature from 115.2 to 110.5 °C and increasing the melting enthalpy from 29.8 to 38.9 J g⁻¹. Thermogravimetric analysis demonstrated improved thermal stability, with the maximum degradation temperature increasing from 325.1 to 343.8 °C and the residual char yield increasing from 5.6% to 16.8%. Specimen S7, containing 6 wt.% MCC and 2 wt.% compatibilizer exhibited the optimum overall performance, achieving a tensile strength of 64 MPa, Young’s modulus of 2500 MPa, impact strength of 5.8 kJ/m², cell viability of 98%, and 88.5% weight loss after 180 days of soil burial. These findings demonstrate that interfacial engineering with MCC and compatibilizer significantly enhances the structural, thermal, mechanical, biological, and biodegradation performance of PLA/PHA biocomposites, making them promising candidates for sustainable advanced packaging and biomedical applications. Full article

Heat pumps are core equipment for efficient low-grade thermal energy utilization and low-carbon transformation of the energy structure, offering significant energy-saving potential in building heating and industrial waste heat recovery. This paper reviews the research progress and technical challenges of compression, absorption, and adsorption heat pumps as well as nanofluid-enhanced heat transfer technology and elastocaloric heat pump systems. Air source heat pumps can delay frosting through variable frequency, heat storage, and waste heat recovery. However, accurate prediction models for performance degradation under extreme cold conditions are lacking. Although ground source and water source heat pumps exhibit significant energy efficiency advantages, ground source systems may suffer from performance degradation due to underground thermal imbalance. The application of water source systems is strictly constrained by water resource conditions. Driven by low-grade waste heat, absorption heat pumps employing traditional working pairs suffer from crystallization, corrosion, or high rectification energy consumption. The COP of a single-effect cycle under 80~100 °C waste heat is only 1.2~1.9, while hybrid cycles can reach approximately 3.2 at 120~150 °C. Although adsorption heat pumps achieve significantly improved performance under continuous heat recovery cycles, the full-scale power density of novel adsorbents such as metal–organic frameworks is inferior to the power density of traditional silica gel. Moreover, under off-design conditions, the performance drops by 23~48% compared to theoretical values. Nanofluids can enhance heat transfer, but the long-term effects of particle agglomeration at high temperatures on pump power consumption and system compatibility remain to be systematically evaluated. Elastocaloric heat pump systems can achieve refrigerant-free cooling, but current prototypes still cannot compete with traditional vapor compression systems in long-cycle fatigue reliability and power density. Current heat pump technologies generally face challenges such as insufficient adaptability to extreme conditions, bottlenecks in working fluids and materials, and a lack of long-term validation. Future research must construct a multi-source coupling optimization system, address common problems in working fluids and materials, promote long-term validation and kilowatt-level prototype demonstrations, and drive the large-scale deployment and engineering application of heat pump technology toward high efficiency, intelligence, and high reliability. Full article

Antarctic microorganisms experience persistent subzero temperatures and repeated freeze–thaw cycles that require specialized mechanisms for survival. Although transcriptomic studies have identified numerous cold-responsive genes, many remain annotated as hypothetical proteins with unknown functions. In this study, we investigated PL002-1792, a strongly upregulated hypothetical protein from Antarctic Flavobacterium sp. PL002 identified under severe cold stress (−20 °C versus −6 °C; log₂ fold change = 5.61, adjusted p = 1.89 × 10⁻¹³⁸). Sequence analysis revealed a 402-amino-acid protein containing a predicted Sec/SPII lipoprotein signal peptide. AlphaFold3 prediction generated a high-confidence structural model (pTM = 0.96) with an elongated β-sheet-rich architecture resembling bacterial ice-binding proteins. Comparative analysis with the ice-binding protein from Flavobacterium frigoris (FfIBP) identified conserved glycine-rich and TXT-like motifs associated with putative ice-binding surfaces. Recombinant PL002-1792 was expressed in Escherichia coli, recovered from inclusion bodies, and successfully refolded into a predominantly β-sheet-rich conformation as confirmed by circular dichroism spectroscopy. Functional assays demonstrated moderate ice recrystallisation inhibition activity, reducing relative ice crystal mean grain size to approximately 90% of the control, and significantly enhanced freeze–thaw survival, with recombinant cells retaining 67% viability after three freeze–thaw cycles compared with 27% for the empty-vector control. These findings identify PL002-1792 as a novel antifreeze-like protein and highlight the utility of structure-guided approaches for uncovering previously uncharacterized cold-adaptation mechanisms in polar microorganisms. Full article

This systematic review aimed to evaluate the effectiveness of indirect cold atmospheric plasma (CAP) in disrupting oral and skin microbial biofilms and to investigate whether the reported effects are mainly attributable to acidic pH, plasma-activated liquids, or specific devices and treatment settings. The review followed PRISMA guidelines and was registered on the Open Science Framework. A comprehensive literature search was conducted across major electronic databases. Studies evaluating indirect CAP on in vitro oral and skin microbial biofilms were included. Comparisons were made with untreated controls, non-activated liquids, and conventional antimicrobials. Outcomes were evaluated based on reductions in biofilm viability or biomass using quantitative assays (e.g., CFU, XTT, and Crystal Violet). Thirteen in vitro studies were included. CFU-based outcomes were reported in 11 of 13 studies (84.61%), and all of these studies showed reductions exceeding 5–6 log under specific conditions. Antimicrobial efficacy varied according to exposure time, microbial species, plasma parameters, and treatment settings, while physicochemical analyses indicated that acidic conditions and plasma-activated liquids play a key role. Indirect CAP appears to be a promising non-invasive antimicrobial strategy for managing oral and skin biofilms. However, variability among devices and settings, together with the absence of clinical data, underscores the need for further standardized studies and clinical investigations. Full article

Polylactic acid (PLA) is a promising bio-based polymer, but its limited thermomechanical stability and low thermal conductivity restrict its use in thermoforming. This study aimed to investigate the influence of polymethylsilsesquioxane (PMSQ) microparticles (5–15 wt.%) on the thermal, mechanical, thermomechanical, rheological, and heat-transfer properties of PLA biocomposites prepared by melt blending and injection molding, with a focus on the thermomechanical properties and thermal conductivity. The results showed that PMSQ acted as an effective nucleating agent, reducing the cold crystallization temperature by up to 14 °C and increasing the crystallinity of PLA, while having little influence on its melting and glass transition temperatures. At 5 wt.% PMSQ, the storage modulus increased by 15% at 35 °C and the thermal conductivity improved by up to 23% at 75 °C, indicating enhanced thermomechanical stability and heat-transfer efficiency. In contrast, tensile strength, yield strength, and impact resistance decreased at higher PMSQ contents (10–15 wt.%), mainly due to particle agglomeration and the formation of defects observed by SEM. Rheological analyses further showed that PMSQ slightly modified the viscoelastic relaxation behavior of PLA. Among the investigated formulations, PLA containing 5 wt.% PMSQ provided the most favorable balance between thermal conductivity, thermomechanical and thermal stability, and mechanical performance. A limitation of the study is that the individual contribution of the coupling agent was not evaluated separately. Overall, the results demonstrate that low PMSQ contents represent an effective strategy for improving the thermal and thermomechanical performance of PLA and highlight the potential of PLA/PMSQ biocomposites for infrared-assisted thermoforming applications. Full article

After cold rolling of high-strength interstitial-free (IF) steel, the ferrite grains undergo plastic deformation associated with the formation of substructures and intense cold-rolling texture, which affects the microstructure and texture in the subsequent annealing process and determines the formability of the final sheet. To clarify the mechanisms of microstructure and texture formation during cold rolling of IF steel, a polycrystalline model was constructed based on the measured microstructure and texture features. A crystal plasticity model, along with a remeshing technique, was developed for IF steel. The model can calculate the deformation of the polycrystal after 70% cold rolling reduction, in which the calculated microstructure and texture features are consistent with the results from electron backscatter diffraction (EBSD). The results show that the deformed microstructure and texture are closely related to the initial crystal orientation, the interaction between neighbouring grains, and the cold rolling reduction. Grains with an initial texture orientation near <001>//ND are more stable during deformation and tend to retain their orientations after cold rolling. In contrast, grains initially deviating from the γ-fiber tend to rotate towards the <111>//ND orientation, while near-γ-fiber grains mainly retain their γ-fiber characteristics with intragranular orientation spreading during cold rolling. Multiple slip systems induce the formation of ingrain shear bands. These results establish a grain-scale link between initial orientation, intragranular substructure formation, and cold rolling texture evolution, and provide a mechanistic basis for optimizing cold rolling texture control and improving the formability of high-strength IF steel sheets. Full article

This study targets biochar utilization in seasonally frozen Northeast China and addresses the insufficient research on aging characteristics and mechanisms of low-temperature wheat straw biochar under long-term freeze–thaw stress. A 60-day simulated freeze–thaw test with 12 h −20 °C freezing and 12 h 0 °C thawing per daily cycle was carried out on 300 °C wheat straw biochar (B300). We tracked dynamic shifts in pH and water absorption during aging, and comprehensively characterized particle size, micromorphology, pore structure, elemental composition and surface functional groups for fresh (CK-B300) and fully aged (FC-B300) biochar. Freeze–thaw cycling caused drastic aging: the average particle size dropped by 33.09%, specific surface area increased by 13.86%, while total pore volume and average pore size fell by 31.47% and 54.9%, respectively. Freeze–thaw oxidation raised the O/C ratio and enriched -OH, C=O functional groups; biochar pH declined by 12.94% alongside improved water absorption. This study confirms that biochar aging is jointly controlled by ice-crystal physical fragmentation and water-temperature oxidation, providing basic data and theoretical support for evaluating and applying biochar in cold freeze–thaw zones. Full article

Persistent microplastics contaminate wastewater systems and pose significant environmental and human health risks due to their small size, buoyancy, persistence, and diverse physicochemical properties, which reduce the effectiveness of conventional treatment technologies. Freeze crystallization, indirect freeze crystallization, eutectic freeze crystallization, and ice-templated separation have emerged as promising long-term technologies for microplastic removal. Particle rejection at the solid–liquid interface, heterogeneous ice nucleation, brine channel formation, and particle entrapment within advancing ice fronts are key crystallization mechanisms governing microplastic separation. Microplastics can adhere to or nucleate growing ice crystals, according to lab and field research. These interactions influence crystal growth kinetics and ice structure formation. Indirect freeze crystallization (IFC) and related chemical-free crystallization systems offer lower energy requirements and improved scalability. Crystallization processes concentrate microplastics for downstream treatment, may connect with photochemical or oxidative degradation at ice interfaces, and are useful in cold areas or low-temperature industrial streams. Despite these advances, several challenges remain, including freezing rate, salinity, particle size distribution, and surface weathering, which are difficult to control. Integrating crystallization into wastewater treatment systems is also difficult. This review covers the latest advances in microplastic–ice interactions, crystallization engineering, and freeze-based separation technologies. It also highlights major knowledge gaps and suggests future research to use crystallization to remove microplastics from wastewater in a sustainable, scalable, and energy-efficient manner. Full article

Obtaining amorphous forms of drugs is one of the ways to increase bioavailability. This is especially important for active pharmaceutical ingredients belonging to class II and IV according to the biopharmaceutical classification. These compounds include the currently widely used fluoroquinolone antibiotics. They have low solubility in water and are therefore typically used as hydrochlorides. The presence of a strong acid and a charged active pharmaceutical ingredient in the drug increases solubility, but can also lead to additional side effects and decreased permeability. One way to improve the properties of active pharmaceutical ingredients is to convert them to amorphous form. In this study, an amorphous form of the fluoroquinolone antibiotic norfloxacin was obtained, its stability was determined, and its solubility was studied. It was shown that the resulting amorphous form has good temporal stability. The optimal models describing the cold crystallization process are the Nakamura and Sbirrazzuoli models. Despite the slower dissolution kinetics compared to the crystalline sample, the amorphous form shows higher equilibrium solubility values. These results can be used in pharmaceutical engineering to produce amorphous forms of active pharmaceutical ingredients and determine their stability. Full article