Search Results (500)

Supercooled large droplets (SLDs), typically defined as droplets with diameters exceeding 100 μm, represent a significant meteorological hazard to aviation safety. Unlike conventional cloud-sized droplets, SLDs have higher inertia and can follow more ballistic trajectories, leading to impingement well aft of leading-edge ice protection systems. SLD icing is further complicated by high-speed splashing, secondary-droplet re-impingement, delayed solidification, and surface water runback. This paper reviews recent progress in understanding SLD impact, splashing, surface water transport, and ice accretion. The review discusses droplet impact on dry and wet surfaces, oblique impingement, ambient-air effects, non-instantaneous solidification, runback dynamics, and downstream ice growth. Emerging ice protection technologies, including superhydrophobic, lubricant-infused, and compliant surfaces, are also evaluated. By synthesizing these developments, this review connects fundamental droplet-impact physics with practical aviation icing challenges and mitigation strategies. Full article

This study employed sodium acetate trihydrate as the phase-change matrix and used a binary nucleating agent composed of disodium hydrogen phosphate dodecahydrate (DHPD) and borax (BX) to suppress supercooling. Sodium carboxymethyl cellulose (CMC) was used as a thickener to mitigate phase separation, and expanded graphite (EG) was introduced as a supporting matrix to enhance thermal conductivity. The composite phase-change material was prepared via melt blending. By means of thermal storage and release performance tests, differential scanning calorimetry and thermal conductivity tests, the effects of the binary nucleating agent ratio, CMC content and EG addition amount on phase-change thermal storage performance, supercooling degree, phase stability and thermal conductivity of the system were systematically investigated. The results indicated that the addition of 3.0 wt% DHPD and 2.0 wt% BX as the binary nucleating agent reduced the supercooling temperature from 20.52 °C to 1.92 °C; 1 wt% CMC effectively suppressed phase separation during thermal cycling; and the incorporation of 3.0 wt% EG increased the thermal conductivity of the composite to 2.92 times that of the pure hydrated salt. Full article

A probability-based model (PBM) is developed to predict the evolution of a population of impinging droplets on a solid substrate and the eventual transition between dropwise and filmwise regimes. A dedicated heat transfer model is designed, in order to estimate the evaporating mass flux when the solid substrate is heated. Statistical information such as the droplet size distribution and the influence of surface wettability, required by the PBM, are derived using a previously developed high-fidelity individual-based model (IBM). The PBM is verified with the high-fidelity model for a small patch of solid substrate. Then, validation with experimental evidence from the literature is carried out in the case of in-flight ice on the NACA0012 airfoil. Results show that the present PBM is capable of investigating in-flight ice problems and can be integrated with a CFD analysis of the air flow past an airfoil flying through a cloud of supercooled droplets to predict the possible onset of ice accretion on the airfoil surface. Compared to Messinger-like models, the influence of surface morphology on runback water flow is incorporated in the PBM through the modeling of a discontinuous wetting layer, contributing to the design of passive and active anti-icing systems. Full article

The rapid development of cold chain logistics has generated a strong demand for high-performance phase change materials (PCMs). In this study, a composite PCM (CPCM) applicable to 5 °C cold chain logistics, integrated with PVA/CMC-Na hydrogel to maintain form stability, is developed. N-Tetradecane and water are employed as the primary cold storage media in the composite. Span 80, Tween 80 and borax are introduced into the composite as homogenizing agents and supercooling depressant, respectively. The main preparation steps of the CPCM include aqueous phase preparation, emulsifier compounding, oil-phase preparation, blending, homogenization, and molding, in sequence. Experimental results demonstrate that the CPCM exhibits a phase transition temperature of 0–5 °C, a latent heat of 236.2 J/g, a supercooling degree of no more than 0.5 °C, and a volume expansion ratio of 3%. Therefore, the CPCM is able to satisfy the cold storage demand for cold chain transportation with a target temperature of approximately 5 °C, and can serve as a superior-performance alternative to the PCMs currently used for similar applications in the market. Full article

Tomicus destruens (Wollaston), the Mediterranean pine shoot beetle, has long been confused with Tomicus piniperda (Linnaeus) in Greece, as well as in many other Mediterranean countries. To clarify its presence and population structure, we analyzed COI sequences of specimens from 21 Greek sites (including islands) and compared them with samples from central (Italy) and western (Spain) Mediterranean populations. Greek populations were dominated by a single haplotype (Td06), whereas Samothraki Island harbored several private haplotypes, indicating long localized lineage persistence. In contrast, Italian and Spanish populations showed high haplotype diversity with many region-specific lineages, consistent with long-term refugial stability in the central-western Mediterranean. Physiological measurements further differentiate the two species: the mean supercooling point (SCP) of Greek T. destruens (–12.3 °C) was substantially higher than reported for T. piniperda (≈–18 °C), demonstrating lower cold tolerance. This supports its restriction to mild Mediterranean climates. Overall, our results confirm the dominant occurrence of T. destruens with no recovery of T. piniperda individuals in Greece and highlight the combined value of genetic and physiological markers for resolving species boundaries and understanding Mediterranean bark beetle biogeography. Full article

External environment shapes the cold adaptation of Ophraella communa, a specialist natural enemy of the invasive common ragweed, and further affects its biological control efficacy. Our study aims to clarify the cold tolerance correlation between ragweed and leaf beetle and explore whether host cold acclimation can enhance the beetle’s low-temperature adaptability. We measured cold-resistant substances, supercooling point (SCP), and chill-coma recovery time (CCRT) of four geographic populations, and conducted indoor low-temperature acclimation of ragweed at 13 °C, 17 °C, 21 °C for 3–9 d, then fed leaf beetle with treated leaves. Results showed that cold-resistant substances in both species varied with latitude and were highly heritable. Cold acclimation can elevate sugars, trehalose, glycerol, and proline in ragweed; the cold tolerance of beetles feeding on these plants was significantly improved. We conclude that cold-resistant substances in ragweed can be trophically transferred to leaf beetle to enhance its cold hardiness, providing a new strategy to improve biocontrol in high-latitude regions. Full article

The chemical control of Leguminivora glycinivorella (Mats.) (Lepidoptera: Tortricidae) has been a major threat to the soybean industry in China over the years. Therefore, we need to develop green, safe, and environmentally friendly alternatives for pest control. Amine hormones, such as melatonin, represent an adjunct strategy for the green control of L. glycinivorella. We aimed to investigate the effects of exogenous melatonin on the development, survival, reproduction, nutrient accumulation, and cold tolerance of L. glycinivorella and to provide insights into the role of melatonin in insect adaptive regulation. Newly hatched L. glycinivorella larvae were fed on soybean pods immersed in solutions with different concentrations of exogenous melatonin. The developmental duration of larvae and pupae, survival rate, pupation rate, adult eclosion rate, body weight and length of larvae and pupae, nutrient composition of mature larvae, adult reproductive parameters, and supercooling and freezing points were measured. With increasing melatonin concentrations, the developmental durations of larvae and pupae were significantly prolonged, while the larval survival rate, pupation rate, and adult eclosion rate significantly decreased. The body weight and length of both larvae and pupae declined with increasing melatonin concentrations, reaching the lowest values in the 200 mg/L group. Melatonin treatment significantly reduced protein and lipid contents in mature larvae but significantly increased glycogen content. Reproductive parameters, including pre-oviposition period, oviposition period, fecundity, and female adult longevity, all decreased significantly with increasing melatonin concentrations. Additionally, melatonin treatment significantly lowered the supercooling point and freezing point of mature larvae. Exogenous melatonin significantly inhibits the growth, development, survival, reproduction, and nutrient metabolism of L. glycinivorella, yet enhances its low-temperature tolerance, suggesting that melatonin may serve as a potential tool for population management of L. glycinivorella through its dual regulatory role in insect physiology. Full article

Mobile thermal energy storage (M-TES) demonstrates significant commercialization potential in industrial waste heat recovery, distributed heating, and clean heating applications, which is primarily based on three technical pathways: sensible heat storage, latent heat storage using phase change materials (PCMs), and thermochemical heat storage. The updated status of M-TES, mainly on PCMs and thermochemical ones, and the challenges facing application were reviewed, and potential development trends were discussed in the present study. Sensible heat storage is relatively mature and cost-effective; however, it suffers from low energy density and comparatively high heat loss during storage and transport. Latent heat storage utilizes the phase transition enthalpy of PCMs to store thermal energy, offering higher energy density and near-isothermal heat release, making it a focal point of current academic and industrial research. Nevertheless, latent heat storage still faces technical bottlenecks, including low thermal conductivity, phase separation, and supercooling of PCMs. Thermochemical heat storage relies on reversible chemical reactions to convert and store thermal energy as chemical energy, theoretically achieving the highest energy density and minimal heat loss. However, due to its technical complexity and high system cost, thermochemical storage remains largely in the early stages of research and demonstration. Overall, as a bridge between heat supply and demand, the development trend emphasizes the design of high-performance composite PCMs, enhanced system integration, and intelligent operational management. However, its large-scale deployment is still constrained by challenges related to energy density, heat transfer enhancement, long-term material stability, and techno-economic feasibility. Full article

This paper documents the preliminary observations and applications of a Ka-band cloud radar newly installed at the Hong Kong International Airport. A special scanning strategy of the cloud radar was developed and is described in detail. The radar provides reasonable cloud base height data as compared with a co-located laser ceilometer, by identifying the lowest vertical layer with reflectivity > −30 dBZ and at least 150 m thick, filtering measurements influenced by rainfall, and removing noise with differential reflectivity thresholds. As demonstrated in a heavy rain case study, the radar provides good estimates of the cloud top height as well, consistent with the cloud liquid water content profiles from a microwave radiometer. The various applications of the cloud radar are then explored, including (1) observations of supercooled liquid water in clouds associated with a late-season tropical cyclone in the South China Sea, (2) monitoring of low visibility in light rain or mist at the airport region using reflectivity as well as Doppler velocity data, and (3) monitoring severe weather such as windshear and turbulence to be encountered by departing aircraft due to low-level jets and initiation of heavy rain, using the Doppler velocity and spectrum data. These observations demonstrated the robustness in the cloud radar in the observation of high clouds and the applicability of the radar’s Doppler velocity in plan position indicator scans under light rain situations. Potential research with the radar, such as visibility maps, turbulence intensity maps, and automatic cloud observations, is also discussed. Full article

Microphysiological systems (MPS) that recapitulate human organ functions have gained attention as alternatives to animal experiments in drug discovery, regenerative medicine, and toxicity assessments. However, preserving MPS with adherent cells remains a significant challenge. In this study, we developed a supercooling preservation method that enables the low-temperature storage of human-derived adherent cells without freezing. Using human hepatic sinusoidal endothelial cells (TMNK-1), we optimized the preservation conditions by assessing the temperature, cooling and rewarming rates, and preservation solutions. Under optimized conditions (preservation at −4 °C, −0.028 °C/min cooling, and +1.0 °C/min rewarming), high cell viability and preserved morphology were maintained for up to 7 days. When these conditions were applied to both two- and three-dimensional MPS containing TMNK-1 or HepG2 cells, post-preservation viability remained high, and no cell death or cytoskeletal disruption was observed. This supercooling preservation method has the potential to serve as a practical strategy for the temporary storage of MPS. Full article

The global population explosion and accelerated industrialization have led to an increasing shortage of fossil fuels and environmental contamination, underscoring the urgent need to develop innovative energy storage technologies to improve energy utilization efficiency. As pivotal components in thermal energy storage (TES) systems, phase change materials (PCMs) enable spatiotemporal matching between thermal energy supply and demand through latent heat absorption and release during phase transitions. Organic PCMs are considered ideal candidates for thermal energy storage due to their high energy storage density, stable phase transition temperature, low supercooling, and negligible phase separation. However, inherent drawbacks such as low thermal conductivity, liquid leakage, limited light absorption, and lack of functionality have hindered their widespread application in advanced thermal management systems. Herein, we systematically summarize cutting-edge functionalization strategies for PCMs, progressing from conventional methods like thermal conductive particle blending and microencapsulation to the emerging design of 3D porous thermally conductive skeletons, including metal foams, boron nitride aerogels, carbon-based aerogels, and MXene aerogels. These frameworks not only enhance thermal transport via continuous conductive pathways and impart shape stability through capillary encapsulation but also, when integrated with photo-thermal, electro-thermal, and magneto-thermal conversion properties, enable broad applications in solar photo-thermal/photo-thermo-electric conversion, thermal management of electronics and batteries, building efficiency, and wearable thermal regulation. The review further addresses current challenges and future directions, highlighting scalable 3D framework fabrication, the shift to active thermal management, and innovative applications beyond conventional domains. By establishing a microstructure–property–application correlation, this work provides valuable insights for developing next-generation high-performance multifunctional phase change composites. Full article

The cloud spatial uniformity in the test section is crucial for icing wind tunnels in aircraft icing research and airworthiness certification. To achieve uniform supercooled large droplet (SLD) icing conditions, both the spatial variation in droplet size distribution and the concentration should be considered. In this study, the spatial distribution of droplets under three SLD conditions is explored in the Aviation Industry Corporation of China Aerodynamics Research Institute (AVICARI)’s FL-61 icing wind tunnel. Measurements are conducted at 12 test points in vertical and horizontal directions using the holographic airborne cloud particle imager (HACPI) in conjunction with a two-axis traversing system. The droplet images obtained at specific test points below the test section centerline show deformation phenomena for droplets larger than 400 $\mathsf{\mu }$m. Additionally, the aspect ratio of deformed droplets increases with droplet size. The spatial evolution of the median volume diameter (MVD) and liquid water content (LWC) is examined. For two spray arrangements where the activated nozzles are positioned close, the test point where the LWC peak in the vertical direction occurs is higher than that of the MVD peak. Further analysis focuses on the size distribution of droplets in the vertical direction. The results show that the settling effect of the droplets larger than 50 $\mathsf{\mu }$m is evident under a flow velocity of 78 m/s. Meanwhile, the position where large droplets tend to appear lowers as the droplet size increases. Finally, the spatial uniformity of droplet size distributions at the same radial distance is discussed. Full article

Bulk metallic glasses exhibit unique viscoplastic flow behavior within their supercooled liquid region. Their high-temperature deformation mechanisms diverge markedly from the highly localized deformation at room temperature. This contrast offers a critical window for investigating their compressive flow models and assessing their forming potential. This study aims to systematically reveal the high-temperature compressive flow behavior of bulk metallic glasses within the supercooled liquid region and to establish a corresponding flow model. Through constant strain rate high-temperature compression experiments conducted on Zr₅₆Co₂₈Al₁₆ bulk metallic glass within its supercooled liquid region, the variations in flow stress, crystallinity, and surface deformation characteristics with temperature were systematically investigated. The results indicate that the compressive behavior of the bulk metallic glass exhibits significant temperature dependence within this temperature range. The compressive strength decreased from 689 MPa at 487 °C to 330 MPa at 507 °C, and then increased to 435 MPa at 527 °C. The angle between the fracture/bulging direction and the loading direction increased from 45° at 487 °C to 88° at 507 °C, and then decreased to 60° at 527 °C. The shear band average spacing increased from 1.797 μm at 487 °C to 2.060 μm at 507 °C, and then decreased to 1.189 μm at 527 °C. These results consistently indicate that the plastic deformability is optimal at a compression temperature of around 510 °C. By integrating the analysis of mechanical curves and morphological characteristics, the applicability of three deformation mechanisms was evaluated: highly localized shear banding, homogeneous viscoplastic flow, and dynamic structural relaxation hardening. A constitutive relationship between compressive strength and temperature was established, which accurately describes their correlation. Simultaneously, it reveals that the dominant deformation mechanism evolves through highly localized shear banding and homogeneous viscoplastic flow, ultimately transforming into dynamic structural relaxation hardening as the temperature increases. This study provides theoretical guidance for predicting the compressive flow behavior of bulk metallic glasses in the supercooled liquid region and offers critical model support for precisely controlling their thermoplastic forming processes. Full article

Cold tolerance of natural enemy insects is a critical determinant of their overwintering survival and efficacy in biological control. The green lacewing (Chrysoperla nipponensis) is an important natural enemy insect that overwinters as adults in nature; however, its high overwintering mortality severely limits its effective application in spring. To investigate the molecular mechanisms underlying low-temperature adaptation, this study focuses on the temperature-sensitive Transient Receptor Potential (TRP) channels and their roles in the cold tolerance of C. nipponensis. The TRPA subfamily gene, Pyrexia-1, was identified and found to be significantly downregulated upon cold exposure. A functional analysis indicates RNAi-mediated knockdown of Pyrexia-1 significantly lowered both the supercooling point and the freezing point of C. nipponensis adults, enhancing their survival rate at −10 °C. These results indicate Pyrexia-1 as a negative regulator of cold tolerance. Further mechanistic investigation revealed that inhibition of Pyrexia-1 function specifically down regulates the expression of trehalase (TRE1) genes, resulting in a marked accumulation of the cryoprotectant trehalose in adults. This metabolic adjustment was accompanied by the upregulation of heat shock protein Hsp70. Overall, these findings establish Pyrexia-1 as a critical molecular switch linking temperature-sensing signals to the metabolic pathways governing freeze resistance, thereby orchestrating the systemic cold adaptation in C. nipponensis. This discovery provides novel insights into the molecular basis of insect low-temperature adaptation and suggests a potential strategy for enhancing the overwintering capacity of natural enemy insects by targeting this regulatory node. Full article

Fresh fish is a highly nutritious and widely consumed product that remains highly perishable due to its chemical composition. Conventional preservation methods, such as chilling and freezing, are effective at inhibiting microbial growth but often compromise nutritional and organoleptic quality. Advanced thermal techniques, including supercooling and cryogenic storage, can extend shelf life to approximately 180 days but involve high infrastructure costs and potential sensory alterations. In response, non-thermal technologies have emerged as promising alternatives capable of minimizing microbial and enzymatic deterioration while reducing oxidative and sensory damage. These include high-pressure processing, cold plasma, gamma irradiation, advanced packaging systems (e.g., modified atmospheres, edible coatings), and natural antioxidants. However, such methods face limitations such as lipid oxidation, flavor changes, and scalability issues, highlighting the need for integrated preservation strategies. This study addresses a critical gap in the application of synergistic, multi-hurdle approaches that combine non-thermal technologies to enhance shelf life without compromising nutritional or sensory quality. It is essential to propose tailored and scalable solutions specific to fishery products to advance the development of sustainable and effective preservation systems that meet the practical needs of the seafood industry. Full article