Search Results (71)

Aerosol–cloud interaction remains one of the largest sources of uncertainty in weather and climate modeling. This study investigates the impacts of aerosols on the macro- and microphysical properties of different cloud types over East Asia, based on nine years of joint satellite observations from CloudSat, CALIPSO, and MODIS, combined with ERA5 reanalysis data. Results reveal pronounced cloud-type dependence in aerosol effects on cloud fraction, cloud top height, and cloud thickness. Aerosols enhance the development of convective clouds while suppressing the vertical extent of stable stratiform clouds. For ice-phase structures, ice cloud fraction and ice water path significantly increase with aerosol optical depth (AOD) in deep convective and high-level clouds, whereas mid- to low-level clouds exhibit reduced ice crystal effective radius and ice water content, indicating an “ice crystal suppression effect.” Even after controlling for 14 meteorological variables, partial correlations between AOD and cloud properties remain significant, suggesting a degree of aerosol influence independent of meteorological conditions. Humidity and wind speed at different altitudes are identified as key modulating factors. These findings highlight the importance of accounting for cloud-type differences, moisture conditions, and dynamic processes when assessing aerosol–cloud–climate interactions and provide observational insights to improve the parameterization of aerosol indirect effects in climate models. Full article

Deicing salt effectively melts ice and snow to maintain traffic flow in seasonal freezing zones, but its erosion effect compromises the water stability and structural integrity of asphalt pavements. To comprehensively explore the impacts of salt erosion on the interfacial behaviors of rubber asphalt–aggregate systems, this study developed a multiscale characterization method integrating a macroscopic mechanical test, microscopic tests, and molecular dynamics (MD) simulations. Firstly, laboratory-controlled salt–freeze–thaw cycles were employed to simulate field conditions, followed by quantitative evaluation of interfacial bonding properties through pull-out tests. Subsequently, the atomic force microscopy (AFM) and Fourier transform infrared spectrometer (FTIR) tests were conducted to characterize the microscopic morphology evolution and chemical functional group transformations, respectively. Moreover, by combining the diffusion coefficients of water molecules, salt solution ions, and asphalt components, the mechanism of interfacial salt erosion was elucidated. The results demonstrate that increasing NaCl concentration and freeze–thaw cycles progressively reduces interfacial pull-out strength and fracture energy, with NaCl-induced damage becoming limited after twelve salt–freeze–thaw cycles. In detail, with exposure to 15 freeze–thaw cycles in 6% NaCl solution, the pull-out strength and fracture energy of the rubber asphalt–limestone aggregate decrease by 50.47% and 51.57%, respectively. At this stage, rubber asphalt exhibits 65.42% and 52.34% increases in carbonyl and sulfoxide indexes, respectively, contrasted by 49.24% and 42.5% decreases in aromatic and aliphatic indexes. Long-term exposure to salt–freeze–thaw conditions promotes phase homogenization, ultimately reducing surface roughness and causing rubber asphalt to resemble matrix asphalt morphologically. At the rubber asphalt–NaCl solution–aggregate interface, the diffusion of Na⁺ is faster than that of Cl⁻. Meanwhile, compared with other asphalt components, saturates exhibit notably enhanced mobility under salt erosion conditions. The synergistic effects of accelerated aging, salt crystallization pressure, and enhanced ionic diffusion jointly induce the deterioration of interfacial bonding, which accounts for the decrease in macroscopic pull-out strength. This multiscale investigation advances understanding of salt-induced deterioration while providing practical insights for developing durable asphalt mixtures in cold regions. Full article

Chicken meat is highly consumed worldwide due to its nutritional value, but its high water content and abundance of polyunsaturated fatty acids make it particularly vulnerable to structural and oxidative damage during freezing and thawing. Slow freezing, in particular, generates large ice crystals that severely impair water-holding capacity (WHC), increase drip loss, promote color deterioration, and intensify protein and lipid oxidation. Innovative thawing strategies are therefore required to mitigate these quality losses. Ultrasound (US) has been successfully applied to accelerate thawing of fast-frozen meat; however, its potential for slowly frozen chicken breast remains poorly understood. This study aimed to evaluate the effects of US-assisted thawing at two frequencies (25 and 130 kHz), two amplitudes (100% and 60%), and three operating modes (normal, sweep, and degas) on the quality of slowly frozen chicken breast. Conventional thawing required 50 min, yielding WHC of 9.87%, drip loss of 4.65%, free sulfhydryls of 16.38 µmol/g, and ∆E of 3.91. In contrast, the optimized US condition (25 kHz, 100% amplitude, sweep mode) thawed samples in only 18 min, with markedly improved WHC (23.14%), reduced drip loss (3.25%), higher preservation of free sulfhydryls (24.69 µmol/g), and minimal color change (∆E = 3.72). Conversely, less effective parameters (e.g., 130 kHz, 60% amplitude, normal mode) prolonged thawing and compromised quality, with WHC dropping to 9.96% and drip loss increasing to 9.05%. Overall, US reduced thawing time under all conditions, but quality responses depended strongly on the applied parameters. The present findings demonstrate the novelty of optimizing US frequency, amplitude, and mode for thawing slowly frozen chicken breast, highlighting sweep mode at 25 kHz and 100% amplitude as the most effective strategy. Future research should explore its scalability and industrial applicability for poultry processing. Full article

The rising demand for convenient, nutritious foods necessitates improved freeze–thaw (F-T) stability in frozen fish balls; however, traditional thermal processing fails to prevent moisture loss, textural degradation, and oxidation. Therefore, this study systematically investigated the effect of ultra-high pressure (UHP) treatment on the quality of golden pomfret fish balls (Trachinotus ovatus) using two-step heating as a control during the F-T cycles. The results showed that compared to two-step heating, UHP significantly reduced the thawing loss (0.68 times) and centrifugal water loss (2.43 times) by enhancing the water-binding capacity (15–20%) and forming denser gel networks. Microstructural analysis revealed that UHP resulted in a more compact internal structure, reduced porosity, altered ice-crystal geometry, and a slower recrystallization rate of the fish balls. Furthermore, UHP effectively reduced protein oxidation (34.53% lower carbonyl increase) and lipid peroxidation (15.6% lower TBARS value) after five F-T cycles compared to the control. Correlation analysis confirmed the dual role of UHP in the regulation of oxidative and structural stability. These findings provide a new technological approach for processing and storing fish balls. Full article

Cold denaturation of gluten proteins during prolonged frozen storage or repeated freeze–thaw cycles can severely affect the quality of frozen cereal products. While both processes have been studied individually, their combined effects and underlying mechanisms remain unclear. This study systematically evaluated the hydration properties and conformational changes in gluten proteins stored at −73 °C and −23 °C, with or without freeze–thaw cycling. Compared to continuous storage, freeze–thaw cycles reduced water-holding capacity by 9.1–12.2% and increased oil-holding capacity by 5.3–10.3%, indicating aggravated structural damage. Ultra-low temperature storage (−73 °C) suppressed ice crystal growth, preserved hydration, and limited hydrophobic residue exposure. Spectroscopic analyses revealed a temperature-dependent shift from α-helices to β-sheets and β-turns, which was accelerated by freeze–thaw cycles. Enhanced hydrophobic interactions and tryptophan exposure further indicated destabilization. Molecular dynamics simulations showed that increased hydrogen bonding between proteins and water contributed to unfolding at low temperatures, while temperature fluctuations intensified denaturation through repeated hydrogen bond breakage and reformation. These results underscore the critical role of thermal instability in cold denaturation and offer mechanistic insights for improving cryoprotection strategies in frozen food systems. Full article

The article is focused on the quantitative assessment of the thermal impact of polar mesospheric clouds (PMCs) on the mesopause caused by the emission of absorbed solar and terrestrial infrared (IR) radiation by cloud particles. For this purpose, a parameterization of mesopause heating by PMC crystals has been developed, the main feature of which is to incorporate the thermal properties of ice and the interaction of cloud particles with the environment. Parametrization is based on PMCs zero-dimensional (0-D) model and uses temperature, pressure, and water vapor data in the 80–90 km altitude range retrieved from Solar Occultation for Ice Experiment (SOFIE) measurements. The calculations are made for 14 PMC seasons in both hemispheres with the summer solstice as the central date. The obtained results show that PMCs can make a significant contribution to the heat balance of the upper atmosphere, comparable to the heating caused, for example, by the dissipation of atmospheric gravity waves (GWs). The interhemispheric differences in heating are manifested mainly in the altitude structure: in the Southern Hemisphere (SH), the area of maximum heating values is 1–2 km higher than in the Northern Hemisphere (NH), while quantitatively they are of the same order. The most intensive heating is observed at the lower boundary of the minimum temperature layer (below 150 K) and gradually weakens with altitude. The NH heating median value is 5.86 K/day, while in the SH it is 5.24 K/day. The lowest values of heating are located above the maximum of cloud ice concentration in both hemispheres. The calculated heating rates are also examined in the context of the various factors of temperature variation in the observed atmospheric layers. It is shown in particular that the thermal impact of PMC is commensurate with the influence of dissipating gravity waves at heights of the mesosphere and lower thermosphere (MLT), which parameterizations are included in all modern numerical models of atmospheric circulation. Hence, the developed parameterization can be used in global atmospheric circulation models for further study of the peculiarities of the thermodynamic regime of the MLT. Full article

The formation and evolution of ice in the Yellow River represent complex dynamic processes. To elucidate the structural characteristics of ice crystals and their governing mechanisms in the Inner Mongolia reach, this investigation utilized high-resolution Sentinel-2 satellite imagery to systematically monitor spatiotemporal variations in open-water formations across diverse channel morphologies throughout the ice regime period. Systematic ice sampling was conducted across diverse channel morphologies of the Yellow River to quantify critical parameters, including crystalline structure characteristics, equivalent diameter distributions, density variations, and sediment content profiles. The results indicate the transformation of open water resulting from various river configurations during the freezing season exhibits distinct characteristics, which are significantly influenced by temperature variations. Ice crystal characterization exhibits that the crystalline structure predominantly manifests as two primary forms: columnar and granular ice formations, with their distribution varying systematically across different channel configurations. Ice crystal morphology exhibits heterogeneity in both form and dimensional characteristics. Columnar ice consistently exhibits larger equivalent diameters compared to granular ice formations. A progressive enhancement in the equivalent diameter of crystals is observed along the vertical axis corresponding to the thickness of the ice during the growth process. The ranges of variation in ice crystal size, ice density, and mud content within ice exhibit differences contingent upon the specific crystal structures present. Observational studies and comparative analyses of ice samples from the Inner Mongolia reach of the Yellow River reveal that channel morphology, ambient thermal conditions, and hydrodynamic parameters are the primary determinants governing the variability in ice microstructure and its associated physical characteristics. This investigation provides fundamental scientific insights and quantitative data that advance our understanding of river ice microstructural characteristics. Full article

Drying constitutes an essential step in aerogel fabrication, where the drying method directly determines the pore structure and consequently influences the material’s functionality. This study employed various drying techniques to prepare balsa-wood-derived aerogels, systematically investigating their effects on microstructure, density, and performance characteristics. The results demonstrate that different drying methods regulate aerogels through distinct pore structure modifications. Supercritical CO₂ drying optimally preserves the native wood microstructure, yielding aerogels with superior thermal insulation performance. Freeze-drying induces the formation of ice crystals, which reconstructs the microstructure, resulting in aerogels with minimal density, significantly enhanced permeability, and exceptional cyclic water absorption capacity. Vacuum drying, oven drying, and natural drying all lead to significant deformation of the aerogel pore structure. Among them, oven drying increases the pore quantity of aerogels through volumetric contraction, thereby achieving the highest specific surface area. However, aerogels prepared by air drying have the highest density and the poorest thermal insulation performance. This study demonstrates that precise control of liquid surface tension during drying can effectively regulate both the pore architecture and functional performance of wood-derived aerogels. The findings offer fundamental insights into tailoring aerogel properties through optimized drying processes, providing valuable guidance for material design and application development. Full article

The environmental impact and resource demands of traditional leather manufacturing have driven the search for sustainable alternatives. Fungal mycelium leather, recognised for its eco-friendly and renewable characteristics, has emerged as a promising option. This study established a cyclic freeze-thaw dehydration protocol for preparing mycelial leather using Ganoderma mycelium produced through liquid fermentation. By precisely controlling the fermentation parameters (pH 5.5, 150 rpm agitation, 28 °C), the liquid fermentation process ensures uniform mycelial growth, which is critical for subsequent structural enhancement during freeze-thaw cycles. After three freeze-thaw cycles were performed at −15 °C, uniformly distributed ice crystals facilitated effective water removal, achieving a minimum moisture content of 47.6%. The optimized freeze-thaw process produced membranes with a tensile strength of 6.22 MPa and elongation at break of 18.92%, demonstrating high mechanical performance. The freeze-thaw process was demonstrated to enhance structural integrity and mechanical properties while offering reduced energy consumption compared to conventional dehydration methods. This research provides a theoretical foundation and technical guidance for optimising fungal mycelium leather production and contributes to the development of sustainable bio-based materials for industrial applications. Full article

The quality of frozen crayfish (Procambarus clarkii) is challenged by freeze–thaw (FT) cycles during storage. The effect of freezing methods on the quality of crayfish during FT cycles was investigated by comparing physicochemical properties, microstructure, and myofibrillar protein (MPs) properties. Three methods were used for crayfish freezing, including air convective freezing (AF) at −20 °C and −50 °C, as well as liquid nitrogen freezing (LNF) at −80 °C. The frozen crayfish were thawed at 4 °C after 45 d of frozen storage as 1 FT cycle. After 5 FT cycles, the water holding capacity of LNF crayfish (70.8%) was significantly (p < 0.05) higher than that of −20 °C AF crayfish (60.6%) and −50 °C AF crayfish (63.5%). The drip loss of LNF crayfish (7.83%) was significantly lower than that of AF crayfish. Moreover, LNF maintained the gel strength and the thermal stability of MPs from crayfish with higher gel storage modulus and enthalpy. These results demonstrated that LNF minimized the formation of large ice crystals, preserving the structural integrity of muscle and the properties of MPs, thereby maintaining crayfish quality. This study investigated the effect of LNF in preserving crayfish quality during FT cycles, providing valuable insights for reducing the quality degradation of aquatic products during storage and transportation. Full article

This study investigated the effect of various concentrations (0.01%, 0.05%, 0.1%, 0.2%, 0.5%) of ice-binding protein from Leucosporidium sp. AY30 (LeIBP) on the freezing efficiency, microstructure, and physicochemical quality of largemouth bass during freeze–thaw cycles and demonstrated the optimal addition conditions of LeIBP. This study found that LeIBP could effectively lower the freezing point of fish without altering the phase transition time significantly. LeIBP can significantly reduce the cross-sectional area and diameter of ice crystals and inhibit recrystallization. LeIBP was found to maintain the stability of protein secondary structure and prevented protein denaturation by increasing the proportion of α-helix. The inclusion of LeIBP retained the water-holding capacity of fish effectively. Furthermore, LeIBP treatment could partially prevent the degradation of fish meat texture. The lightness and whiteness values of fish treated with LeIBP were increased, while the redness and yellowness values were decreased. At the end of freeze–thaw cycle, the LeIBP-treated group presented pH values similar to fresh fish. Overall, 0.05% LeIBP was observed to be the most effective concentration to inhibit ice crystal growth, thereby maintaining the quality of the fish. Full article

The crystal structure and topology analyses of a new bromo-Mn(II) complex with 2,4-bis(3,5dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (MBPT) were reported. Its structure was confirmed using single-crystal X-ray diffraction to create the formula [Mn(MBPT)Br(H₂O)₂]ClO₄. Its crystal system was monoclinic and its space group was p2₁. The Mn(II) was coordinated with MBPT as a NNN-pincer ligand, with one bromide ion in the equatorial plane. The two axial terminals were occupied by two trans water molecules. H…H, N…H, Br…H, C…H and O…H were the predominant intermolecular contacts, while Br…H, O…H and C…O were the significant contacts based on Hirshfeld analysis. Moreover, anion–ᴨ interaction was found between C(s-triazine) and O(perchlorate). This complex had better antioxidant activity than the free ligand (MBPT). In addition, the cytotoxicity of the [Mn(MBPT)Br(H₂O)₂]ClO₄ complex showed better results against HepG-2 and MCF-7 cells, recording IC₅₀ values of 31.11 ± 2.04 and 50.05 ± 2.16 µM, respectively, compared to the free ligand (IC₅₀ = 671.44 ± 21.41 and 1113.55 ± 29.77 µM). In comparison to cis-platin as a reference drug, the IC₅₀ values were 63 and 80 μM, respectively, which indicated the promising anticancer activity of the studied compound against both cell lines. In terms of the safety of normal cells, the Mn(II) complex recorded a high IC₅₀ value of 359.10 ± 8.72 µM against the WI-38 non-cancerous cell line. The complex showed better activity towards Staphylococcus aureus, Bacillus subtilis, and Proteus vulgaris relative to the free MBPT, but had low to moderate activity compared to Gentamycin as an antibacterial positive control. Full article

Freezing storage is the most common method of food preservation and the formation of ice crystals during freezing has an important impact on food quality. The water molecular structure, mechanism of ice crystal formation, and ice crystal structure are elaborated in the present review. Meanwhile the methods of ice crystal characterization are outlined. It is concluded that the distribution of the water molecule cluster structure during the crystallization process directly affects the formed ice crystals’ structure, but the intrinsic relationship needs to be further investigated. The morphology and distribution of ice crystals can be observed by experimental methods while simulation methods provide the possibility to study the molecular structure changes in water and ice crystals. It is hoped that this review will provide more information about ice crystallization and promote the control of ice crystals in frozen foods. Full article

The premelting layer on crystal surfaces significantly affects the stability, surface reactivity, and phase transition behaviors of crystals. Traditional methods for studying this layer—experimental techniques, classical simulations, and even first-principle simulations—have significant limitations in accuracy and scalability. To overcome these challenges, we employ molecular dynamic simulations based on neural network potentials to investigate the structural and dynamic behavior of the premelting layer on ice. This approach matches the accuracy of first-principle calculations while greatly improving computational efficiency, allowing us to simulate the ice–vapor interface on a much larger scale. In this study, we conducted a one-nanosecond simulation of the ice–vapor interface involving 1024 water molecules. This significantly exceeds the time and size scales of previous first-principle studies. Our simulation results indicate complete surface melting. Furthermore, our simulation results reveal dynamic heterogeneity within the premelting layer, with molecules segregated into clusters of low and high mobility. Full article

The porosity of freshwater ice and sea ice is one of the main parameters that determine their strength. The strength of ice varies over a wide range of values, and the differences in the intensity of the mechanisms of ice porosity formation in different water areas can be one of the possible reasons for these variations. The water mass contains gases in two forms: gases dissolved in the water mass, as well as gas bubbles that are formed when wind waves break up, and bubbles that float up from the seabed. This article presents the results of an analysis of the role of each of these forms in the formation of gas inclusions (pores) in the crystal structure of ice. The results showed that the main source of gas pores in ice crystals is the gas bubbles coming to the surface from the bottom, formed during the decomposition of bottom sediments or during gas leaks from near-bottom oil and gas fields. The possibility of gas bubbles occurring and rising to the ice–water boundary depends on the presence of bottom sources of the gases, the intensity of dissolution of the bubbles and the depth of the water area. Therefore, the variation in the porosity and the strength of ice over the space of the water areas can be associated with the changes in their depths, and the presence and location of the natural gas sources. Full article