Ice Crystals Research Articles

Cell-compatible isotonic freezing media enabled by thermo-responsive osmolyte-adsorption/exclusion polymer matrices

During the long-term storage of cells, it is necessary to inhibit ice crystal formation by adding cryoprotectants. Non-cell-permeable cryoprotectants have high osmotic pressure which dehydrates cells, indirectly suppressing intracellular ice crystal formation. However, the high osmotic pressure and dehydration often damage cells. Emerging polymer-type non-cell-permeable cryoprotectants form matrices surrounding cells. These matrices inhibit the influx of extracellular ice nuclei that trigger intracellular ice crystal formation. However, these polymer-type cryoprotectants also require high osmotic pressure to exert an effective cryoprotecting effect. In this study, we designed a poly(zwitterion) (polyZI) that forms firm matrices around cells based on their high affinity to cell membranes. The polyZI successfully cryopreserved freeze-vulnerable cells under isotonic conditions. These matrices also controlled osmotic pressure by adsorbing and desorbing NaCl depending on the temperature, which is a suitable feature for isotonic cryopreservation. Although cell proliferation was delayed by the cellular matrices, washing with a sucrose solution improved proliferation.

A Numerical Simulation Study of Secondary Ice Productions in a Squall Line Case

Secondary ice productions (SIPs) can produce ice crystals with a number concentration much higher than that of ice nucleating particles in mixed-phase clouds and therefore influence cloud glaciation and precipitation. For midlatitude continental mesoscale convective systems (MCSs), how SIPs affect the microphysical properties and precipitation is still not clear. There are few studies of SIPs in midlatitude continental MCSs. This study investigates the roles of three SIPs (rime splintering, freezing drop shattering, and ice-ice collisional breakup) on a squall line case in North China on 18 August 2020 using the WRF model with a modified Morrison double-moment bulk microphysical scheme. Including SIPs, especially ice-ice collisional breakup, in the model simulations markedly improves the simulated convective area and convective precipitation rate of the squall line, while slightly improving the area and precipitation of the stratiform region. Within the mixed-phase layer in both the convective and stratiform regions of the squall line, ice-ice collisional breakup is the dominant process to generate ice crystals. In contrast, rime splintering generates an order of magnitude fewer ice crystals than ice-ice collisional breakup, while freezing drop shattering plays a negligible role due to the lack of large drops. Ice multiplication through ice-ice collisional breakup and rime splintering produces numerous snowflakes and graupel. This leads to enhanced depositional growth and weaker riming, which in turn weakens rime splintering. It is recommended to add SIP parameterization to the model.

Seasonal and Diurnal Variation of Lightning Over Java Region and Its Relationship with Aerosol

This study discusses the influence of aerosols on lightning on Java Island using monthly and diurnal observation data from the Tropical Rainfall Measuring Mission (TRMM) for 16 years (1998 - 2013). Aerosol Optical Depth (AOD) was obtained from The Modern Era Retrospective Analysis for Research and Applications version 2 (MERRA-2). Aerosol and lightning data are grouped into rainy (December-January-February) and dry (June-July-August) seasons and diurnal data grouped per 3 hours. The intensity of lightning strikes in the western part of Java Island, such as Jakarta and Banten, is higher than the eastern region, in accordance with the aerosol distribution pattern. The influence of aerosols and lightning in the rainy and dry seasons is relatively stable. However, influence of aerosols on lightning diurnally changes significantly. The strongest correlation between aerosol and lightning was recorded in the afternoon (r = 0.8) and evening (r = 0.9). Although the influence of aerosols on radiation reaches a saturation point during the day, the movement of land and sea breezes plays a dominant role. At night, the influence of aerosols on surface temperature is weakened due to the absence of solar radiation, so aerosols help the electrification of clouds through the formation of ice crystals.

Ice accretion compositions in ice crystal icing

Ice crystal icing is a major hazard in aviation from the perspectives of aerodynamic deterioration, flight safety and operability. To counter this challenge, existing ice prediction tools require more accurate modeling of sticking efficiency of glaciated ice crystals on heated substrates. As part of the present study, icing wind tunnel experiments have been performed to quantify the volumetric liquid water fraction in the ice layers, the sticking efficiency of impacting ice crystals and the maximum thickness of ice layers accreted on a dedicated test article for a wide range of experimental conditions. To achieve this objective, two measurement techniques, calorimetry and capacitive measurements, have been employed to quantify the average liquid water content and the distribution of liquid in the ice layers. The experiments show that when switching from negative to positive wet bulb temperatures, the sticking efficiency and maximum thickness of ice layers increase significantly. A similar trend is observed for increasing substrate heat flux, which results in an increasing liquid fraction in the ice layer measured by calorimetry, as well as increasing sticking efficiency and maximum thickness of the ice layers. Increasing the ice water content does not have a significant influence on the liquid content, but leads to more pronounced erosion effects. The conducted experiments provide an unprecedented insight into the liquid distribution in ice accretions and its effect on the sticking efficiency. These results provide a sound basis for more accurate modeling of sticking efficiency and enhances the understanding of ice accretion processes.

Estimation of sea ice drift and concentration during melt season using C-band dual-polarimetric Sentinel-1 data

Characterizing sea ice changes over the Arctic can give proper insight into its extent in the current context of climate change. Sea ice motion's effect on ice area is influenced by seasonal conditions and the prevailing climate. However, the motion of thinner ice during the melt season can result in polynyas and cause significant ice loss that lasts the entire year. Sea ice drift and concentration during melt season are rarely discussed. The present study attempts to estimate sea ice drift during the melt season (July–August) using Differential Synthetic Aperture Radar Interferometry (DInSAR) with the usability of C-band Sentinel-1 data. The displacements/drifts were estimated using the phase shifts between two complex images with a temporal extent of 12 days. The study also proposed estimating sea ice concentration using polarimetric descriptors (power, purity, and randomness). The results revealed drifts of about 14–15 cm in the northeastern and southern parts followed by 45–50 cm in the middle parts and 20–25 cm along the coasts and open areas. Based on three polarimetric descriptors, thin ice and other ice fragments over open areas have shown less sea ice concentration as compared to the more concentrated pancake and pack ice with more compactness over the ice crystals. The study can be useful for computing drift in the melt season and carrying out spatiotemporal time-series analysis of seasonal sea ice drift/deformation studies. The algorithm and results can be used as a base study for the upcoming L- and S-band carrying NASA-ISRO Synthetic Aperture Radar (NISAR) mission.

Abundant production of dimethylsulfoniopropionate as a cryoprotectant by freshwater phytoplanktonic dinoflagellates in ice-covered Lake Baikal

Phytoplanktonic dinoflagellates form colonies between vertical ice crystals during the ice-melting season in Lake Baikal, but how the plankton survive the freezing conditions is not known. Here we show that the phytoplankton produces large amounts of dimethylsulfoniopropionate (DMSP), which is best-known as a marine compound. Lake-water DMSP concentrations in the spring season are comparable with those in the oceans, and colony water in ice exhibits extremely high concentrations. DMSP concentration of surface water correlates with plankton density and reaches a maximum in mid-April, with temperature-dependent fluctuations. DMSP is released from plankton cells into water in warm days. DMSP is a characteristic osmolyte of marine algae; our results demonstrate that freshwater plankton, Gymnodinium baicalense, has DMSP-producing ability, and efficiently uses the limited sulfur resource (only 1/500 of sea sulfate) to survive in freshwater ice. Plankton in Lake Baikal do not need an osmolyte, and our results clearly indicate that DMSP plays a cryoprotective role. DMSP, although a characteristic marine compound, could also be an important zwitterion for algae of other boreal lakes, alpine snow, and glaciers.

Effect of static magnetic field-assisted freezing at different temperatures on muscle quality of pacific white shrimp (Litopenaeus vannamei)

The effect of static magnetic field-assisted freezing (MF) at different temperatures (−35, −30, −25, and −20 °C) on the muscle quality of pacific white shrimp (Litopenaeus vannamei) was evaluated to investigate the possibility of energy saving by MF. The results showed that the −35 °C MF treatment increased the water-holding capacity of shrimp muscle, and maintained the wholeness of the microstructure compared to −35 °C immersion freezing (control group, IF). With the increase in freezing temperature in the MF treatments, the size of ice crystals gradually increased, and the sensory properties of shrimp decreased. The water-holding capacity, sensory properties, and water distribution of shrimp muscle subjected to MF at −25 °C were still no significantly different from those of the IF at −35 °C (P > 0.05). In summary, the utilization of MF enhanced the quality of frozen pacific white shrimp, which has the potential to provide energy saving benefits.

Quantitative Analysis of Ice Crystal Growth During Freezing of Dimethyl Sulfoxide Solutions Under Alternating Current Electric Fields.

During cryopreservation, the growth of ice crystals can cause mechanical damage to samples, which is one of the important factors limiting the quality of preserved samples. To enhance the preservation quality of biological samples, scholars have tried various engineering methods. Among them, an electric field is an essential factor affecting solution freezing. Dimethyl sulfoxide, as a commonly used cryoprotectant, can cause mechanical damage to cells due to ice crystals even when freezing at the optimal freezing rate. Water is a strongly polar dielectric material, and the applied alternating current (AC) electric field will affect the water freezing performance. Therefore, a quantitative study of ice crystal nucleation and growth during freezing of dimethyl sulfoxide solutions under different AC electric field conditions is needed to try to reduce ice crystal damage. We created a liquid-film device to approximate the ice crystal growth process as a two-dimensional image. The frequency of the AC voltage was set from 0 to 50 kHz. We measured the supercooling of the dimethyl sulfoxide solution under AC electric field conditions. As an objective and accurate quantitative analysis of the ice crystal growth process, we propose a Dilated Convolutional Segmentation Transformer for semantic segmentation of ice crystal images. It is concluded that the average area and the growth rate of single ice crystals decrease with increasing electric field frequency at a certain concentration of dimethyl sulfoxide solution. Lower concentrations of dimethyl sulfoxide solution in combination with an AC electric field can achieve similar ice suppression effects as when higher concentrations of dimethyl sulfoxide solution act alone. We believe that AC electric fields are expected to be an aid to cryopreservation and provide some theoretical basis and experimental foundation for its development.

A physics-based sphericity, drag coefficient and Nusselt number model of a partially-melted ice crystal

Partially melted crystals can lead to ice accretion on heated surfaces including the inside of turbofan engines. To model the ice accretion due to partially melted crystals, the trajectory of the crystals must be modeled based on their drag, which is correlated with the shape of the crystals. The melting rate of an ice crystal is subject to the heat transfer coefficient, which is influenced by the geometry of an ice crystal. The geometries of partially melted crystals are related to their percentage melting. To study the correlation between the geometry and the percentage melting of a crystal, a levitating test rig is used to study the melting process of a single crystal under natural convection. The percentage melting is measured using luminescent Rhodamine B. A transient collapse in the shape of a single ice crystal is observed in the experiment during the melting process. The shape variation is predicted by a physics model based on the surface energy at the interface between air, ice and water. The model shows that the critical percentage melting forcing the crystal to become spherical is independent of the initial shape of the crystal. The average critical percentage melting that collapses the crystal to a spherical shape was experimentally measured to be 68.6%. A physics based model predicts such critical percentage melting to be 62.2%, verifying the proposed model. A two-stage drag coefficient model is also developed to capture the transient crystal shape at the predicted critical percentage of melting.

Guar-based aerogels with oriented lamellar structure and lightweight properties for flame-retardant and thermal insulation

In this study, a multi-functional guar gum aerogel with the oriented lamellar structure, which introduced sodium silicate (Na2O·nSiO2) and phytic acid (PA) as thermal insulation additives and flame-retardant agents, respectively, was fabricated via freeze drying. Our aerogel's chemical structure, morphology, and thermal and mechanical properties were analyzed. The oriented lamellar structure was attributed to the orientated growth of ice crystals, which was induced by the “silicate-guar, guar-phytate, and phytate-silicate” multiple hydrogen bonds formed between Na2O·nSiO2, PA, and guar gum. The density of the sample with 2 wt% PA could reach 0.0335 g·cm−3, and the porosity was 5 %, along with a specific pore volume of 0.8144 cm3·g−1. The mechanical properties and thermal insulation performed significant differences in the radial and axial direction of the oriented lamella (nearly 100 % resilience while 50 % deformation quantity and 0.0235 W/(m*K) of thermal conductivity in the radial direction, up to 0.079 MPa of compressive strength in the axial direction). The presence of PA attached a good flame-retardant ability to our aerogel (The Limiting Oxygen Index (LOI) was 30.77 %). This work provides a novel and promising method for developing anisotropic aerogel with excellent potential in building energy efficiency and flame-retardant.

CLASS Observations of Atmospheric Cloud Polarization at millimeter Wavelengths

The dynamic atmosphere imposes challenges to ground-based cosmic microwave background observation, especially for measurements on large angular scales. The hydrometeors in the atmosphere, mostly in the form of clouds, scatter the ambient thermal radiation and are known to be the main linearly polarized source in the atmosphere. This scattering-induced polarization is significantly enhanced for ice clouds due to the alignment of ice crystals under gravity, which are also the most common clouds seen at the millimeter-astronomy sites at high altitudes. This work presents a multifrequency study of cloud polarization observed by the Cosmology Large Angular Scale Surveyor experiment on Cerro Toco in the Atacama Desert of northern Chile, from 2016–2022, at the frequency bands centered around 40, 90, 150, and 220 GHz. Using a machine-learning-assisted cloud classifier, we made connections between the transient polarized emission found in all four frequencies with the clouds imaged by monitoring cameras at the observing site. The polarization angles of the cloud events are found to be mostly 90° from the local meridian, which is consistent with the presence of horizontally aligned ice crystals. The 90 and 150 GHz polarization data are consistent with a power law with a spectral index of 3.90 ± 0.06, while an excess/deficit of polarization amplitude is found at 40/220 GHz compared with a Rayleigh scattering spectrum. These results are consistent with Rayleigh-scattering-dominated cloud polarization, with possible effects from supercooled water absorption and/or Mie scattering from a population of large cloud particles that contribute to the 220 GHz polarization.

Retarding ice recrystallization by tamarind seed polysaccharide: Investigation in ice cream mixes and insights from molecular dynamics simulation

Food hydrocolloids, such as naturally sourced polysaccharide stabilizers, are becoming potential candidates for retarding ice recrystallization in frozen desserts. Tamarind seed polysaccharide (TSP) and its depolymerized fraction (DTSP) possessed ice recrystallization retardation (IRR) activity by a splat cooling assay. This study is a follow-up work aiming to investigate their application effects to retard ice recrystallization in ice cream mixes (ICMs) and delve into the ice-binding behavior at the ice/water interface. Native TSP worked for or against IRR in the ICMs depending on the concentration, while DTSP possessed an increased IRR effect under the addition of higher concentration (3.0%). Compared to TSP, adding DTSP caused less of an increase in the viscosity of the ICMs. Molecular dynamics was used to simulate ice growth in the presence of TSP (oligomer) and showed that the TSP possessed activity for retarding ice growth along the prismatic planes. During the propagation of ice crystals, the TSP was bound onto the ice and caused evident structural defects of ice layers. The findings of this study proved that TSP and DTSP have a promising application to retard ice recrystallization in ice cream and shed new light on understanding the mechanism of natural polysaccharides to retard ice growth.

Postmortem histological freeze-thaw artifacts: a case report of a frozen infant and literature review.

Freezing and thawing have the potential to alter the gross and histologic appearance of tissues, causing damage to individual cells and disrupting the overall architecture. In forensic investigations, freezing and thawing can play a crucial role in cases of unknown cause of death. Perpetrators may use freezing preservation to conceal the body or obscure the time of death. Freezing can also occur naturally when a body is exposed to the elements, sometimes even leading to death itself. We present a case report involving an autopsy performed on an infant, who died of natural causes, after undergoing freezing and thawing. The objective of this study was to identify and discuss the histological artifacts observed in different tissues as a result of the freeze-thaw process. Histologically, the infant's tissues exhibited the most common features described in the literature. Ice crystal artifacts, characterized by expansion of the extracellular space and tissue clefts, were found in the heart, brain, liver, lungs, and kidneys. On the contrary, adipose tissue was not affected, likely due to the scarcity of water. Freeze-thaw artifacts should be taken into account whether a body is known to have been frozen or to add further data if found already defrosted.

Thermal insulating and mechanical properties of high entropy pyrochlore oxide ceramic with hierarchical porous structures

High entropy pyrochlore oxide ceramics with hierarchical porous structures were prepared by coprecipitation, freeze-casting, and press-less sintering methods. In the fabrication process, a Ca2+-crosslinked alginate network was utilized to control the growth of ice crystals, resulting in uniformly dispersed micro-scale circular pores. The submicron pores were formed in the high entropy oxide ceramic during the press-less sintering method. The XRD was employed to explore the phase of the high entropy pyrochlore oxide ceramic. The porous structures of high-entropy ceramic were analyzed through the discussion of microstructure and pore size distribution. The tests show that the prepared series of ceramics with high porosity have optional compressive strength and thermal insulation properties. The high entropy oxide ceramic (La0.2Y0.2Gd0.2Sm0.2Nd0.2)2Zr2O7 with hierarchical porous structures possess moderate density (0.4 g/cm3) and low thermal conductivity (0.04 W m−1 K−1). The excellent comprehensive performance makes the porous high entropy oxide ceramic could be applied as a thermal insulating material.

Cryoprotective effect of soybean oil on surimi gels and the mechanism based on molecular dynamics simulation.

The effect of soybean oil (SO) on freeze-thaw (F-T)-treated surimi was investigated and its related mechanism was revealed by molecular dynamics (MD) simulations. The results displayed that SO has a disrupting effect on the structure of fresh samples. However, in the F-T-treated samples, surimi gels supplemented with SO had a more uniform microstructure. Simultaneously, when SO was added from 0% to 7% in the F-T-treated samples, the gel strength increased from (p < .05), the physically bound water was increased from 92.90% to 94.15% (p < .05), and storage modulus was increased from 5939 to 6523 Pa. Triglycerides of SO generated hydrophobic interactions with myosin mainly in carbon chains. Computational results from MD simulations illustrated that the structure of myosin combined with triglycerides was more stable than that of myosin alone during temperature fluctuations (-20 to 4°C). During ice crystal growth, triglycerides absorbed on the myosin surface inhibited the growth of surrounding ice crystals and mitigated the ice crystal growth rate (from 7.54 to 5.99 cm/s). The addition of SO during the F-T treatments allowed myosin to be less negatively affected by ice crystal formation and temperature fluctuations and ultimately contributed to the formation of a more uniform network gel structure.

Freeze-thaw stability of Pickering emulsion stabilized by modified soy protein particles and its application in plant-based ice cream

Pickering emulsions are of great interest to the food industry and their freeze-thaw stability important when used in frozen foods. Particles of soybean isolate (SPI) were heat treated and then crosslinked with transglutaminase (TG) enzyme to produce Pickering emulsions. The protein particles produced using unheated and uncrosslinked SPI (NSPI) was used as the benchmark. The mean particle size, absolute zeta potential, and surface hydrophobicity of protein particles produced using heat treatment and TG crosslinking (at 40 U/g) SPI (HSPI-TG-40) were the highest and substantially higher than those produced using NSPI. The thermal treatment of protein particles followed by crosslinking with TG enzyme improved the freeze-thaw stability of Pickering emulsions stabilized by them. The Pickering emulsions produced using HSPI-TG-40 had the lowest temperature for ice crystal formation and they had better freeze-thaw stability. The plant-based ice cream prepared by HSPI-TG-40 particle-stabilized Pickering emulsions had suitable texture and freeze-thaw stability compared to the ice cream produced using NSPI. The Pickering particles produced using heat treatment of SPI followed by crosslinking with TG (at 40 U/g) produced the most freeze-thaw stable Pickering emulsions. These Pickering particles and Pickering emulsions could be used in frozen foods such as ice cream.

Wildfire smoke triggers cirrus formation: lidar observations over the eastern Mediterranean

Abstract. The number of intense wildfires may increase further in upcoming years as a consequence of climate change. It is therefore necessary to improve our knowledge about the role of smoke in the climate system, with emphasis on the impact of smoke particles on the evolution of clouds, precipitation, and cloud radiative properties. Presently, one key aspect of research is whether or not wildfire smoke particles can initiate cirrus formation. In this study, we present lidar observations over Limassol, Cyprus, from 27 October to 3 November 2020, when extended wildfire smoke fields crossed the Mediterranean Basin from Portugal to Cyprus. We found strong evidence that aged smoke (organic aerosol particles) originating from wildfires in North America triggered significant ice nucleation at temperatures from −47 to −53 ∘C and caused the formation of extended cirrus layers. The observations suggest that the ice crystals were nucleated just below the tropopause in the presence of smoke particles serving as ice-nucleating particles (INPs). The main part of the 2–3 km thick smoke layer was, however, in the lower stratosphere just above the tropopause. With actual radiosonde observations of temperature and relative humidity and lidar-derived smoke particle surface area concentrations used as starting values, gravity wave simulations show that the lofting of air by 100–200 m is sufficient to initiate significant ice nucleation on the smoke particles, leading to ice crystal number concentrations of 1–100 L−1.

Effect of sodium alginate ice glazing on the quality of the freeze-thawed fish balls

The effect of 1.0 % (w/v) sodium alginate (SA) glazing on surface frost formation and the quality of frozen fish balls in repeated freeze-thaw (F-T) cycles was studied. The optimal glazing property of 1.0 % SA solution was manifested by high transmittance, excellent water resistance, and high ice glazing rate. After seven F-T cycles, compared with the control, the ice production, thawing loss, and total volatile base nitrogen (TVB-N) value of samples with 1.0 % ice glazing decreased by 28.30 %, 21.02 %, and 27.35 %, while the chewiness and whiteness were increased by 15.02 % and 10.40 %, respectively. Moreover, compared to the control, the microstructure of fish balls glazed with 1.0 % SA was smoother and more uniform, and the ice crystal diameter was smaller. Therefore, 1.0 % SA glazing effectively inhibits the formation of ice crystals, reducing water migration and loss while minimizing damage to the meat structure, thus enhancing the quality of meat products.

The roles of undercooling degree and materials surface configuration in the growth mechanism of ice layer caused by micro-droplets

Effect mechanisms of the undercooling degree and the surface configuration on the ice growth characteristics were revealed under micro-droplets icing conditions. Preferential ice crystals appear firstly on the surfaces due to the randomness of icing, and obtain growth advantages to form protruding structures. Protruding structures block the incoming droplets from contacting the substrates, causing voids around the structures. The undercooling degree mainly affects the density and the growth rate of preferential ice crystals. With the increase of undercooling degree, the preferential ice crystals have higher density and growth rate, resulting in stronger growth advantage and higher porosity. The surface configuration affects the growth mode, and the ice layer grows with uniform mode, spreading mode and structure-induced mode on the aluminum, smooth Polytetrafluoroethylene (PTFE) and rough PTFE surface respectively, causing the needle-like, ridge-like and cluster-like ice crystals. The rough structures effectively improve the porosity of the ice layer, which is beneficial for optimizing the icephobic property of the materials. This paper provides important theoretical guidance for the design of subsequent icephobic materials.

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

Antifreeze proteins (AFPs) bind to ice in solutions, resulting in non-colligative freezing point depression; however, their effects on ice nucleation are not well understood. The predominant plasma AFP of winter flounder (Pseudopleuronectes americanus) is AFP6, which is an amphiphilic alpha helix. In this study, AFP6 and modified constructs were produced as fusion proteins in Escherichia coli, subjected to proteolysis when required and purified prior to use. AFP6 and its recombinant fusion precursor generated similar thermal hysteresis and bipyramidal ice crystals, whereas an inactive mutant AFP6 produced hexagonal crystals and no hysteresis. Circular dichroism spectra of the wild-type and mutant AFP6 were consistent with an alpha helix. The effects of these proteins on ice nucleation were investigated alongside non-AFP proteins using a standard droplet freezing assay. In the presence of nucleating AgI, modest reductions in the nucleation temperature occurred with the addition of mutant AFP6, and several non-AFPs, suggesting non-specific inhibition of AgI-induced ice nucleation. In these experiments, both AFP6 and its recombinant precursor resulted in lower nucleation temperatures, consistent with an additional inhibitory effect. Conversely, in the absence of AgI, AFP6 induced ice nucleation, with no other proteins showing this effect. Nucleation by AFP6 was dose-dependent, reaching a maximum at 1.5 mM protein. Nucleation by AFP6 also required an ice-binding site, as the inactive mutant had no effect. Furthermore, the absence of nucleation by the recombinant precursor protein suggested that the fusion moiety was interfering with the formation of a surface capable of nucleating ice.