Ice Crystals Research Articles

Sperm freezing damage: the role of regulated cell death.

Substantial progress in research on sperm cryopreservation has occurred since the twentieth century, especially focusing on improving sperm freezing procedures and optimizing semen extenders. However, the cellular biological mechanisms of sperm freezing damage are still unclear, which greatly restricts the promotion and development of sperm cryopreservation. An essential component of sperm freezing damage is the occurrence of cell death. Considering the existence of multiple types of cell death pathways, this review discusses connections between characteristics of regulated cell death (e.g., apoptosis and ferroptosis), and accidental cell death (e.g., intracellular ice crystals) with sperm freezing damage and explores possible future research directions in this field.

Reversal of crystallization in cryoprotected samples by laser editing.

Advances in cryobiology techniques commonly target either the cooling or the warming cycle, while little thought has been given to ≪repair≫ protocols applicable during cold storage. In particular, crystallization is the dominant threat to cryopreserved samples but proceeds from small nuclei that are innocuous if further growth is forestalled. To this end, we propose a laser editing technique that locally heats individual crystals above their melting point by a focused nanosecond pulse, followed by amorphization during rapid resolidification. As a reference, we first apply the approach to ice crystals in cryoprotected solution and use Raman confocal mapping to study the deactivation of crystalline order. Then, we examine dimethyl sulfoxide trihydrate crystals that can germinate at low temperatures in maximally freeze concentrated regions, as commonly produced by equilibrium cooling protocols. We show how to uniquely identify this phase from Raman spectra and evidence retarded growth of laser-edited crystals during warming.

Effect of fumigation height and time on cryopreservation of ram semen

The cooling rate is a crucial factor in the process of freezing semen, influencing the overall freezing effectiveness. The height and time of fumigation can significantly impact the rate of cooling. Appropriate cooling rates can help minimize the formation of ice crystals in spermatozoa and reduce potential damage to them. Therefore, the aim of this study was to evaluate the effect of different fumigation heights and time for the cryopreservation of Hu ram semen. Experiments I–IV assessed the effect of semen cryopreservation by testing the post-thawed spermatozoa total motility (TM), progressive motility (PM) and kinetic parameters fumigated at distances of 2, 4, 6 and 8 cm for durations of 5, 10, 15 and 20 min, respectively. Based on the results of experiments I to IV, experiment V evaluated the effect of semen cryopreservation by testing the post-thawed spermatozoa TM, PM, kinetic parameters, plasma membrane integrity, acrosome integrity and reactive oxygen species (ROS) level fumigated at distances of 2, 4, 6 and 8 cm for duration of 20 min. The results indicated that fumigation at 2 cm for 20 min significantly (P < 0.05) improved spermatozoa TM, PM, mean angular displacement (MAD), plasma membrane integrity and acrosome integrity compared to other groups. Additionally, it significantly (P < 0.05) reduced spermatozoa ROS level compared to the 6 and 8 cm groups. In conclusion, fumigation for 20 min at a distance of 2 cm from the liquid nitrogen surface is the most suitable cooling method for the cryopreservation of Hu ram semen.

Elucidation of the Role of TRPV1, VEGF-A, TXA2, Redox Homeostasis, and Inflammatory Cascades in Protection against Cold Injuries by Herbosomal-Loaded PEG-Poloxamer Topical Formulation.

High-altitude regions, cold deserts, permafrost regions, and the polar region have some of the severest cold conditions on earth and pose immense perils of cold injuries to exposed individuals. Accidental and unintended exposures to severe cold, either unintentionally or due to occupational risks, can greatly increase the risk of serious conditions including hypothermia, trench foot, and cold injuries like frostbite. Cold-induced vasoconstriction and intracellular/intravascular ice crystal formation lead to hypoxic conditions at the cellular level. The condition is exacerbated in individuals having inadequate and proper covering and layering, particularly when large area of the body are exposed to extremely cold environments. There is a paucity of preventive and therapeutic pharmacological modalities that have been explored for managing and treating cold injuries. Given this, an efficient modality that can potentiate the healing of frostbite was investigated by studying various complex pathophysiological changes that occur during severe cold injuries. In the current research, we report the effectiveness and healing properties of a standardized formulation, i.e., a herbosomal-loaded PEG-poloxamer topical formulation (n-HPTF), on frostbite. The intricate mechanistic pathways modulated by the novel formulation have been elucidated by studying the pathophysiological sequelae that occur following severe cold exposures leading to frostbite. The results indicate that n-HPTF ameliorates the outcome of frostbite, as it activates positive sensory nerves widely distributed in the epidermis transient receptor potential vanilloid 1 (TRPV1), significantly (p < 0.05) upregulates cytokeratin-14, promotes angiogenesis (VEGF-A), prominently represses the expression of thromboxane formation (TXA2), and significantly (p < 0.05) restores levels of enzymatic (glutathione reductase, superoxide dismutase, and catalase) and nonenzymatic antioxidants (glutathione). Additionally, n-HPTF attenuates oxidative stress and the expression of inflammatory proteins PGF-2α, NFκB-p65, TNF-α, IL-6, IL-1β, malondialdehyde (MDA), advanced oxidative protein products (AOPP), and protein carbonylation (PCO). Masson's Trichrome staining showed that n-HPTF stimulates cellular proliferation, and increases collagen fiber deposition, which significantly (p < 0.05) promotes the healing of frostbitten tissue, as compared to control. We conclude that protection against severe cold injuries by n-HPTF is mediated via modulation of pathways involving TRPV1, VEGF-A, TXA2, redox homeostasis, and inflammatory cascades. The study is likely to have widespread implications for the prophylaxis and management of moderate-to-severe frostbite conditions.

Liquid–liquid transition and ice crystallization in a machine-learned coarse-grained water model

Mounting experimental evidence supports the existence of a liquid-liquid transition (LLT) in high-pressure supercooled water. However, fast crystallization of supercooled water has impeded identification of the LLT line TLL(p) in experiments. While the most accurate all-atom (AA) water models display a LLT, their computational cost limits investigations of its interplay with ice formation. Coarse-grained (CG) models provide over 100-fold computational efficiency gain over AA models, enabling the study of water crystallization, but have not yet shown to have a LLT. Here, we demonstrate that the CG machine-learned water model Machine-Learned Bond-Order Potential (ML-BOP) has a LLT that ends in a critical point at pc = 170 ± 10 MPa and Tc = 181 ± 3 K. The TLL(p) of ML-BOP is almost identical to the one of TIP4P/2005, adding to the similarity in the equation of state of liquid water in both models. Cooling simulations reveal that ice crystallization is fastest at the LLT and its supercritical continuation of maximum heat capacity, supporting a mechanistic relationship between the structural transformation of water to a low-density liquid (LDL) and ice formation. We find no signature of liquid-liquid criticality in the ice crystallization temperatures. ML-BOP replicates the competition between formation of LDL and ice observed in ultrafast experiments of decompression of the high-density liquid (HDL) into the region of stability of LDL. The simulations reveal that crystallization occurs prior to the coarsening of the HDL and LDL domains, obscuring the distinction between the highly metastable first-order LLT and pronounced structural fluctuations along its supercritical continuation.

A comprehensive investigation of the use of freeze concentration appro aches for the concentration of fish protein hydrolysates

Fish protein hydrolysates (FPH) are inherently unstable in their liquid form, necessitating either freezing or dewatering for stabilization. Gentle methods such as freeze concentration can be used to remove water, this can be achieved by freezing water in solution by decreasing the bulk temperature below freezing point and separating pure ice crystals from concentrated solution. This approach serves as an alternative to techniques like evaporation and reverse osmosis for concentrating solutions that have high water content, significant nutritional value, and thermolabile compounds. This is crucial as many bioactive compounds degrade when exposed to elevated temperatures. Another notable advantage of this technology is its potential to reduce energy consumption by up to 40% when integrated into the FPH drying process. Although this technology is currently industrialized primarily for juices, it can achieve concentrations of up to 60°Brix and manage viscosities up to 400 mPa.s. Numerous studies have been dedicated to enhancing design and processes, leading to a 35% reduction in the system's capital cost and a 20% reduction in energy consumption. Moreover, freeze concentration can synergize with other concentration techniques, creating more efficient hybrid processes. This review aims to introduce freeze concentration as a superior option for preserving fish protein hydrolysates, enhancing their stability, and maintaining their nutritional and bioactive qualities.

Very high frequency radiation emitted by negative narrow bipolar events occurred over malacca strait

In this paper, Very-High Frequency (VHF) radiation pulses associated with 11 negative Narrow Bipolar Events (NBEs) produced by a tropical storm over Malacca Strait are examined. The lightning data were recorded from a measurement station (ST) which consisted of a fast antenna (FA) and three VHF sensors (two 5 m perpendicular baselines interferometer). The average rise time (RT), average zero-crossing time (ZCT), average pulse duration (PD), and range of peak currents of the negative NBEs were 1.4 ± 0.4 μs, 2.7 ± 1.0 μs, 12.0 ± 6.9 μs, and −10 to −64 kA, respectively. The key finding is that all VHF radiation pulses have been found to precede the negative NBEs with an average lead time of 0.7 ± 0.3 μs. An interferometer map for one negative NBE (labelled as NBE10) detected at 35.7 km from ST has shown a characteristic of mixed propagation direction of fast streamers. The first VHF radiation source was detected at 12.4 ± 0.4 km above sea level. The total length and estimated velocity of the main propagation of the VHF radiation sources were 2.2 ± 0.7 km and between 1.4 × 108 and 2.8 × 108 ms−1, respectively. Moreover, based on the Himawari satellite image, the maximum extent of the cloud top height was estimated to be around 20.9 km over sea level (over Malacca Strait). All the VHF radiation sources associated with NBE10 were suggested to be detected above the main negative charge region (6 km altitude that corresponds to −10 °C). Thus, it could be suggested that NBE10 was initiated most likely in the environment of the ice crystals alone, based on the first altitude of the VHF radiation source and maximum extent of cloud top height.

Effect of Turbulence on the Collision Rate between Settling Ice Crystals and Droplets

Abstract In mixed-phase clouds, graupel forms by riming, a process whereby ice crystals and supercooled water droplets settling through a turbulent flow collide and aggregate. We consider here the early stage of the collision process of small ice crystals with water droplets and determine numerically the geometric collision kernel in turbulent flows (therefore neglecting all interactions between the particles and assuming a collision efficiency equal to unity), over a range of energy dissipation rate 1–250 cm2 s−3 relevant to cloud microphysics. We take into account the effect of small, but nonzero fluid inertia, which is essential since it favors a biased orientation of the crystals with their broad side down. Since water droplets and ice crystals have different masses and shapes, they generally settle with different velocities. Turbulence does not play any significant role on the collision kernel when the difference between the settling velocities of the two sets of particles is larger than a few millimeters per second. The situation is completely different when the settling speeds of droplets and crystals are comparable, in which case turbulence is the main cause of collisions. Our results are compatible with those of recent experiments according to which turbulence does not clearly increase the growth rate of tethered graupel in a flow transporting water droplets.

Probing the Interaction Between Biomolecules Under Sub-Zero Temperature Conditions by Electrophoresis in Ice Grain Boundaries

BackgroundPsychrophiles can survive under cryogenic conditions because of various biomolecules. These molecules interact with cells, ice crystals, and lipid bilayers to enhance their functionality. Previous studies typically measured these interactions by thawing frozen samples and conducting biological assays at room temperature; however, studying these interactions under cryogenic conditions is crucial. This is because these biomolecules can function at lower temperatures. Therefore, a platform for measuring chemical interactions under sub-zero temperature conditions must be established. ResultsThe chemical interactions between biomolecules under sub-zero temperature conditions were evaluated within ice grain boundaries with a channel-like structure, which circumvents the need for thawing. An aqueous solution of sucrose was frozen within a microfluidic channel, facilitating the formation of freeze-concentrated solutions (FCSs) that functioned as size-tunable electrophoretic fields. Avidin proteins or single-stranded DNA (ssDNA) were introduced into the FCS in advance. Probe micro/nanospheres whose surfaces were modified with molecules complementary to the target analytes were introduced into the FCS. If the targets have functionalities under sub-zero temperature conditions, they interact with complementary molecules. The chemical interactions between the target molecules and nanospheres led to the aggregation of the particles. The size tunability of the diameter of the FCS channels enabled the recognition of aggregation levels, which is indicative of interaction reactivity. The avidin–biotin interaction and ssDNA hybridization served as models for chemical interactions, demonstrating interactivity under sub-zero temperature conditions. The results presented herein suggest the potential for in situ measurement of biochemical assays in the frozen state, elucidating the functionality of bio-related macromolecules at or slightly below 0°C. SignificanceThis is the first methodology to evaluate chemical interactions under sub-zero temperature conditions without employing the freeze-and-thaw process. This method has the advantage of revealing the chemical interactions only at low temperatures. Therefore, it can be used to screen and evaluate the functionality of cryo-related biomolecules, including cold-shock and antifreeze proteins.

Visualization of intracellular ice formation and growth in mouse oocytes

BACKGROUND: Characterization of intracellular ice formation (IIF) in oocytes during the freezing and thawing processes will contribute to optimizing their cryopreservation. However, the observation of the ice formation process in oocytes is limited by the spatiotemporal resolution of the cryomicroscope systems. OBJECTIVE: To observe the intracellular icing of oocytes during cooling and rewarming, and to study the mechanism of formation and growth of intracellular ice in oocytes. MATERIALS AND METHODS: Mouse oocytes were frozen at different cooling rates to induce intracellular ice formation using a cryomicroscopy system consisting of a microscope equipped with a cryogenic cold stage, an automatic cooling system, a temperature control system, and a high-speed camera. The growth patterns of intracellular ice in oocytes were analyzed from the images recorded. Finally, the growth rate of intracellular ice formation in oocytes was calculated using an automatic intracellular ice tracking method.RESULTS: The IIF temperature decreased gradually with the increase in cooling rate. Initiation sites of IIF could be classified into three categories: marginal type, internal type and coexisting type. There was a strong predominance for ice crystal initiation site in the oocytes, with up to 80% of the initiation sites located in the marginal region. The intracellular ice growth modes of darkening and twitching cells were characterized by “spreading” and “clustering”, respectively. In addition, twitching cells started to recrystallize during rewarming, while darkening cells did not. The instantaneous maximal growth rate of ice crystals in twitching cells was about 10 times higher than that in darkening cells. CONCLUSION: By visualising the growth of ice crystals in mouse oocytes during cooling and rewarming, we obtained valuable information on the kinetics of ice formation and melting in these cells. This information can help us understand how ice formation and melting affect the viability and quality of oocytes after cryopreservation.

Ice/salt assisted synthesis of ultrathin two-dimensional nitrogen doped carbon nanosheets for fast lithium storage

Two-dimensional carbon nanosheets have garnered considerable interest as promising anode materials in energy storage devices due to their large specific surface area and excellent conductivity. The efficient synthesis of ultrathin nitrogen-doped carbon nanosheets is achieved with the aid of cysteine, employing a green ice/salt-assisted strategy. Ice influences the growth direction of salt crystals and determines the distribution of sodium lignosulfonate on the surfaces of both ice and salt crystals. The introduction of methionine incorporates heteroatoms, altering the electronic structure and chemical activity of the material, thereby effectively enhancing its lithium storage performance. The initial charge capacity of the optimized sample reached 766.4 mA h g−1 at a current density of 0.2 A g−1, maintaining a capacity of 571.1 mA h g−1 after 100 cycles. This study presents an innovative method for fabricating ultrathin carbon nanosheets using eco-friendly, cost-effective sodium lignosulfonate, showcasing a promising candidate for lithium-ion batteries and future energy storage technologies.

Effect of freezing rates on α-amylase enzymatic susceptibility, in vitro digestibility, and technological properties of starch microparticles

The aim of this study was to evaluate the effect of freezing rates using direct (LF: Liquid nitrogen) and indirect (RF: Cryogenic refrigerator and UF: ultra-freezer) methods at temperatures of (−20, −80, and − 196 °C) on the enzymatic susceptibility with α-amylase for microparticles. In vitro digestibility parameters and technological properties were also analyzed. Lower rates resulted in larger ice crystals, damaging the starch structure. Hydrolysis was more pronounced at slower rates RF: 0.07 °C/min and UF: 0.14 °C/min, yielding maximum values of RDS: 37.63% and SDS: 59.32% for RF. Type A crystallinity remained unchanged, with only a noted increase in crystallinity of up to 6.50% for FR. Starch pastes were classified as pseudoplastic, with RF exhibiting superior textural parameters and apparent viscosity. (RF: 7.18 J g−1 and UF: 7.34 J g−1) also showed lower values of gelatinization enthalpy. Freezing techniques were viable in facilitating the diffusion of α-amylase and reducing RS by up to 81%.

Simulation of freezing a sea water droplet moving in a cold air

A rapid freezing of a sea water droplet moving in a cold air is modeled. A droplet freezing model is a key component needed for computational forecasting of ice accretion on surfaces of ships and other equipment operating in low-temperature regions. The freezing process consists of the three stages: 1) water cooling to the incipient solidification temperature; 2) liquid solidification; 3) further freezing of the primarily solidified droplet. An icy region, being formed during the 2nd stage, initially represents a slurry, composed of ice crystals suspended in water. Further cooling is associated with an increase in the crystal concentration that at a certain threshold causes slurry transformation into a spongy (porous) ice. The solidification stage model is composed of the three coupled differential equations formulated in the moving coordinate system. All the physical and thermophysical water properties, required for modeling droplet freezing, are calculated by using the empirical correlations. The set of the equations is solved numerically. The solidification process is illustrated by computational examples for different droplet sizes and water salinities. The computed icy region thickness vs. time, as well as temperature distributions and porosities along droplet radius at different time moments are shown.

Freeze–thawed characteristics of lactone tofu under the synergy of low‐frequency electrostatic field

AbstractThe formation and melting of ice crystals bring undesirable changes to the gel structure of frozen food. To explore the role of Low‐frequency electrostatic field (LFE‐field) in the freeze–thaw quality of protein‐rich foods, the freezing temperature, thawing temperature, and the participation of the LFE‐field were used as variables to orthogonally optimize the treatment of tofu. The sensory score, color, moisture, aerobic bacterial count, and micromorphology were recorded to evaluate the quality variation of tofu. When be frozen at −50°C and thawed at 10°C, tofu maintains 91.1% hardness and 87.0% elasticity hinging on the effect of LFE‐field. When be frozen at −60°C in LFE‐field and thawed at 10°C, tofu maintains 90.7% hardness and 89.7% elasticity. The LFE‐field treatment also increased the water retention capacity and reduced the damage of ice crystals to the protein matrix structure of tofu. In addition, the LFE‐field has minimal impact influence on the tofu's color.Practical applicationsThe low‐frequency electrostatic field (LFE‐field) treatment increased the water retention capacity and reduced the damage of ice crystals to the protein matrix structure of tofu during the freeze–thaw process. In the future, the small LFE‐field could easily be installed in refrigerator and used for long time freezing preservation protein rich food to extend its shelf life and improve the storage quality, such as cheese, tofu, etc.

Composition-antifreeze property relationships of gelatin and the corresponding mechanisms

The inherent functional fractions (gelation and ice-affinitive fractions) of gelatin enable it as a promising cryoprotectant alternative. However, the composition-antifreeze property relationships of gelatin remain to be investigated. In this study, the HW-PSG and LW-PSG fractions of gelatin from fish scales were obtained, according to the critical gelation conditions and ice-binding measurements, respectively. Thermal hysteresis (THA) value, associated with ice nucleation, of LW-PSG was higher than that of HW-PSG. Besides, the relatively low-sized ice crystals (210–550 μm2) indicated that HW-PSG showed strong ice recrystallization inhibition (IRI) ability, compared to other groups. These results suggested that LW-PSG inhibited ice nucleation, while HW-PSG displayed the strong IRI ability. Furthermore, the antifreeze mechanisms were clarified through IRI measurements and molecular dynamics simulation. The minimum size of ice crystals was found for HW-PSG gels with dense microstructure, suggesting the HW-PSG retarded the growth of ice crystals by restricting the migration and phase transformation of water molecules. The hydrogen bond interactions between the ice crystal surface and ASN1294 and PRO1433 residues of LW-PSG, and hydrophobic interactions contributed to inhibiting the nucleation of ice crystals. This study provided some references to further enhance antifreeze performance of gelatin by modulating fragment composition.

The crystallization properties of antifreeze GelMA hydrogel and its application in cryopreservation of tissue-engineered skin constructs.

Gelatin methacrylate (GelMA) hydrogels are expected to be ideal skin tissue engineering dressings for a wide range of clinical treatments. Herein, we report the preparation of GelMA or antifreeze GelMA hydrogel sheets with different GelMA concentrations, crosslinking times, and cryoprotectant (CPA) concentrations. The crystallization properties of GelMA or antifreeze GelMA hydrogel sheets were studied by cryomicroscopy and differential scanning calorimetry (DSC). It was found that the growth of ice crystals was slower when GelMA hydrogel concentration was more than 7%. The 10% DMSO-7% GelMA hydrogel sheets crosslinked for 60 min showed no ice crystal formation and growth during cooling and warming. The DSC results showed that the vitrification temperature of the 10% DMSO-7% GelMA hydrogel sheet was -111°C. Furthermore, slow freezing and rapid freezing of fibroblast-laden GelMA or antifreeze GelMA hydrogel sheets, and tissue-engineered skin constructs were studied. The results showed no significant difference in cell survival between slow (88.8% ± 1.51) and rapid (89.2% ± 3.00) freezing of fibroblast-loaded 10% DMSO-7% GelMA hydrogel sheets, and significantly higher than that of 7% GelMA hydrogel sheets (33.4% ± 5.46). The cell viability was higher in tissue-engineered skin constructs after slow freezing (86.34% ± 1.45) than rapid freezing (72.74% ± 1.34). We believe that the combination of antifreeze hydrogels and tissue engineering will facilitate the cryopreservation of tissue engineering constructs.

A numerical study of heterogeneous nucleation of ice crystals and frost layer growth on horizontal cold surfaces

In engineering applications, the formation and growth of frost layers can significantly affect the normal operation of equipment, leading to undesirable influences. Therefore, it is imperative to understand the frost formation mechanisms as a basis for developing effective anti-frosting and defrosting methodologies. This study proposes a model for the growth of horizontal cold surface frost layers using the classical nucleation theory and the Eulerian multiphase flow model. Compared to numerous models that investigate the frost formation issues using the computational fluid dynamics (CFD) method, our proposed model takes into account the crystal growth period (the heterogeneous nucleation process of ice). The predicted results of the proposed model were found to be in good agreement with the data collected from five related experimental studies. In this regard, the maximum frost layer thickness error was 23.9 % with a mean error of 5.1 %, and the maximum density error was 22.8 % with a mean error of 8.1 %. Compared to existing models in the literature, the proposed model can reduce the maximum thickness and density uncertainties by 17.4 % and 10.2 %, respectively. Additionally, the effects of the surface contact angle and environmental parameters on the nucleation process were analyzed using the established model. It was found that a larger contact angle, higher cold surface temperature, and lower air temperature, humidity, and velocity were unfavorable conditions for supporting the formation and growth of ice crystals. Moreover, the nucleation completion time was shortened with the increase in the moist air supersaturation degree, varying as an exponential function. The findings of this study provide an important theoretical basis for the development of optimizing strategies for anti-frosting and defrosting.

Effect of bovine hide gelatin antifreeze peptides on the quality of frozen dough treated with freeze-thaw cycles and its steamed bread

The structure of frozen dough was damaged due to the recrystallization of ice crystals during freeze-thawing. Therefore, the effect of bovine hide gelatin antifreeze peptides (BgAFPs) on the quality of frozen dough treated with freeze-thaw cycles and its steamed bread was investigated. The results showed that BgAFPs exhibited a high thermal hysteresis activity at 1.64 °C and possessed the significant ability to inhibit ice crystals growth due to its -Gly-X-Y- (where X was mostly proline or hydroxyproline, Y was any amino acid) repeating sequences. The decrease in gassing rate of frozen dough without BgAFPs (41.31%) was significantly greater than those of frozen dough with BgAFPs (36.32%, 27.74% and 24.30%), revealing that the BgAFPs had cryoprotective effect on yeast cells. Additionally, BgAFPs maintained a continuous apparent morphology of the frozen dough by inhibiting water migration. Specifically, the freezable water content in the frozen dough with 0% and 1.0% BgAFPs increased from 63.35% and 59.41% to 73.74% and 64.36%, respectively. Furthermore, BgAFPs increased the specific volume and springiness, decreased the hardness of the steamed bread. These results suggested that BgAFPs effectively attenuated the freeze-thaw induced damage to frozen dough and improved the quality of steamed bread.

Structure of Molecular Water and the 3D Pythagoras Theorem

Water ice crystals inherently embed in their shape complex hexagonal structures, emerging mostly due to the O-H bond angle 104.5 degrees being close to the 120 degrees found in hexagons. This article explores the possible integration of water molecules into a recently published mathematical architecture called the Universal Gear model. Already published in a mathematics peer-reviewed journal, the Universal Gear is an orthogonally-intertwined construct of Pythagoras theorem driven planes, that all together provide a perfect balance in terms of the three main equations governing three-dimensional existence: zero net sum of lengths, zero net sum of areas and zero net sum of volumes. Computer-aided Design shows how a group of (simplified and realistic) water molecules successfully integrate into the (regular and irregular) version of the Universal Gear. Interestingly the geometric pattern that emerges from the projected field of water molecules integrated into the Universal Gear is a structure already observed in monuments of ancient civilizations. The ambient conditions, in terms of pressure and temperature, where such a structure could appear is not yet known, requiring further research preferably using computational molecular dynamics.

Shear behavior of cement-stabilized silty clay exposed to low-temperature curing

Cement-stabilized soils are widely used in civil engineering applications. However, they inevitably encounter low-temperature curing conditions, particularly in cold regions. In this study, shear experiments were conducted on cement-stabilized silty clays with different dry densities, cement contents, curing ages and temperatures. The factors influencing the shear performance of cement-stabilized soils were analyzed. The results showed that the peak value of the shear stress-displacement curve of the cement-stabilized silty clay increased with the vertical pressure, and the failure patterns for soils with and without cement significantly differed. Generally, the soils without cement underwent ductile failure, whereas the cement-stabilized soils experienced brittle failure. The shear strength and cohesion of the cement-stabilized soils increased with cement content, dry density, curing age and temperature. In addition, the ice and hydration products significantly influenced the internal friction angle of the cement-stabilized soils. An optimal cement content for silty clay was determined to obtain the largest internal friction angle, which ranged from 12% to 15%. Furthermore, at the curing temperature of −2 °C, the edge-face contact form accounted for the majority with a relatively high porosity, but the morphology of C-S-H changed from a sheet-like form to reticulate structure when the curing temperature increased to 22 °C. However, the contribution of the ice crystals to the shear strength was less significant than that of the hydration products. This study provides insights into the mechanical and microstructural properties of cement-stabilized soils in cold-region geotechnical construction.