Frozen State Research Articles

Biogenesis and Regulation of the Freeze–Thaw Responsive microRNA Fingerprint in Hepatic Tissue of Rana sylvatica

Background: Freeze-tolerant animals undergo significant physiological and biochemical changes to overcome challenges associated with prolonged whole-body freezing. In wood frog Rana sylvatica (now Lithobates sylvaticus), up to 65% of total body water freezes in extracellular ice masses and, during this state of suspended animation, it is completely immobile and displays no detectable brain, heart, or respirometry activity. To survive such extensive freezing, frogs integrate various regulatory mechanisms to ensure quick and smooth transitions into or out of this hypometabolic state. One such rapid and reversible regulatory molecule capable of coordinating many aspects of biological functions is microRNA. Herein, we present a large-scale analysis of the biogenesis and regulation of microRNAs in wood frog liver over the course of a freeze–thaw cycle (control, 24 h frozen, and 8 h thawed). Methods/Results: Immunoblotting of key microRNA biogenesis factors showed an upregulation and enhancement of microRNA processing capacity during freezing and thawing. This was followed with RT-qPCR analysis of 109 microRNA species, of which 20 were significantly differentially expressed during freezing and thawing, with the majority being upregulated. Downstream bioinformatics analysis of miRNA/mRNA targeting coupled with in silico protein–protein interactions and functional clustering of biological processes suggested that these microRNAs were suppressing pro-growth functions, including DNA replication, mRNA processing and splicing, protein translation and turnover, and carbohydrate metabolism. Conclusions: Our findings suggest that this enhanced miRNA maturation capacity might be one key factor in the vital hepatic miRNA-mediated suppression of energy-expensive processes needed for long-term survival in a frozen state.

Global and Local Shear Behavior of the Frozen Soil–Concrete Interface: Effects of Temperature, Water Content, Normal Stress, and Shear Rate

The interface between soil and concrete in cold climates has a significant effect on the structural integrity of embedded structures, including piles, liners, and others. In this study, a novel temperature control system was employed to conduct direct shear tests on this interface. The test conditions included normal stress (25 to 100 kPa), temperature (ranging from 20 to −6 °C), water content (from 10 to 19%), and shear rates (0.1 to 1.2 mm/min). Simultaneously, the deformation process of the interface was continuously photographed using a modified visual shear box, and the non-uniform deformation mechanism of the interface was analyzed by combining digital image correlation (DIC) technology with the photographic data. The findings revealed that the shear stress–shear displacement curves did not exhibit a discernible peak strength at elevated temperatures, indicating deformation behavior characterized by strain hardening. In the frozen state, however, the deformation softened, and the interfacial ice bonding strength exhibited a positive correlation with decreasing temperature. When the initial water content was 16% and the normal stress was 100 kPa, the peak shear strength increased significantly from 99.9 kPa to 182.9 kPa as the test temperature dropped from 20 °C to −6 °C. Both shear rate and temperature were found to have a marked effect on the peak shear strength, with interface cohesion being the principal factor contributing to this phenomenon. At a shear rate of 0.1 mm/min, the curve showed hardening characteristics, but at other shear rates, the curves exhibited strain-softening behavior, with the softening becoming more pronounced as shear rates increased and temperatures decreased. Due to the refreezing of interfacial ice, the residual shear strength increased in proportion to the reduction in shear rate. On a mesoscopic level, it was evident that the displacement of soil particles near the interface exhibited more pronounced changes. At lower shear rates, the phenomenon of interfacial refreezing became apparent, as evidenced by the periodic changes in interfacial granular displacement at the interface.

Influence of flocculation with dry-mixing on slump flow of high-strength concrete

The use of high-strength concrete in construction is expected to increase, and the manufacturing technology employed to produce such concrete needs to adapt to this rise. High-strength concrete has a workability that can vary significantly depending on the mixing conditions, even with the same mix design and in the same environment. This research focuses on the change in workability due to dry-mixing (i.e., mixing of fine aggregate with cement in the early stage) in the mixing process of a high-strength concrete mix using a revolving-double paddle mixer. As a result, it was confirmed that the slump flow value difference caused by dry-mixing was about 25 cm. Furthermore, Cryo-SEM (which can observe the specimens in the frozen state) image analysis revealed that dry-mixing causes flocculation of cement particles. The amount of admixtures adsorbed was then analyzed. This study concluded that flocculation affects the degree and timing of admixture adsorption in the later stages of the mixing process, leading to differences in concrete workability.

Experimental study of heat pipe start-up characteristics and development of an enhanced model considering gas diffusion effects

Heat pipe-based cooling reactors, offering passive heat transfer and modularity, are becoming the preferred type for micro-reactors. Alkali metals such as sodium, potassium and lithium are usually used as the working medium of the heat pipe, which is in a frozen state at normal atmospheric temperature. After heating the heat pipe, the working medium will melt and enter the gas chamber, and its flow state will undergo a transition from discontinuous flow to continuous flow. The start-up of the heat pipe affects the heat export and neutron physical characteristics of the heat pipe cooling reactor. Building a model of heat pipe can predict the start-up of heat pipe effectively, which can be helpful to study the start-up and safety analysis of heat pipe cooling reactor. In this paper, a heat pipe flat-front model considering the gas diffusion effect is established, and the gas temperature distribution characteristics in the non-continuous flow region are obtained through the start-up experiment of heat pipe. The calculated results of the flat-front model considering gas diffusion effect and the vertical flat-front model are compared with the experiment. The results show that the model in this paper can better describe the start-up of heat pipe. At the same time, the evaporation and condensation coefficient model based on temperature change is used to deal with the evaporation and condensation mass flow at the phase change interface of the heat pipe, which can better describe the temperature difference at the interface of the heat pipe.

Experimental investigation on the thermal performance of high temperature two-phase loop thermosyphon

High-temperature two-phase loop thermosyphons (TPLTs) have the potential to be applied in high-temperature thermochemical conversions, concentrated solar energy, and nuclear energy. However, there has been limited investigation on the thermal performance of TPLTs so far. This work experimentally examines the thermal performance of TPLTs using alkali metals (NaK alloy and pure Na) as working fluids, aiming for internal energy recovery of a double-riser reactor. The effects of filling ratios (FRs), heating temperature, and altitude difference between the evaporator and condenser are investigated regarding start-up characteristics and steady-state performance. The experimental results show that the TPLT with NaK as the working fluid can successfully complete the start-up when the heating temperature is set to above 650 °C under the test conditions. However, the TPLT using pure Na as the working fluid can't successfully complete the start-up from a frozen state without a preheating operation. According to the variations in thermal resistance, an FR of 38% in the TPLT allows for the best heat-transfer performance under steady state when compared to the conditions that FRs are equal to 25% and 50%. Additionally, placing the condenser slightly higher than the evaporator is beneficial for improving the steady-state performance. However, if the condenser is lower than the evaporator, its steady-state performance is remarkably degraded.

Biophysical and permeability characterization of lyophilized (freeze-dried) human cadaver skin

The in vitro permeation testing (IVPT) of topical products is performed across the human cadaver skin, which is stored frozen for a prolonged duration. The cryo-preservation technique is not economical and is a cumbersome process. Moreover, prolonged skin preservation in a frozen state and frequent freeze-thawing are known to affect the integrity of the skin barrier. Therefore, lyophilization was explored as an alternative to protect the skin tissue from microbial contamination and degeneration. Notably, the project's objective was to investigate the impact of the freeze-drying process on the skin's barrier properties. The morphometrics of the lyophilized skin were measured. Histological studies did not reveal any notable changes in the organization and intactness of the layers due to the freeze-drying process. The biophysical attributes of the skin, such as transepidermal water evaporation rate and transepidermal electrical resistivity (TEER), were not significantly different between the control skin (not subjected to the freeze-drying process) and the freeze-dried skin (FDS). The permeability of caffeine, a hydrophilic model permeant, and nicotine, a lipophilic model permeant, were consistent across the control and the FDS. It is evident from the studies that the lyophilization process did not significantly impact the barrier properties and permeability of the skin.

The impact of repeated temperature cycling on cryopreserved human iPSC viability stems from cytochrome redox state changes.

Human induced pluripotent stem cells (hiPSCs) are an attractive cell source for regenerative medicine. For its widespread use as a starting material, a robust storage and distribution system in the frozen state is necessary. For this system, managing transient warming during storage and transport is essential, but how transient warming affects cells and the mechanisms involved are not yet fully understood. This study examined the influence of temperature cyclings (from -80°C to -150°C) on cryopreserved hiPSCs using a custom-made cryo Raman microscope, flow cytometry, and performance indices to assess viability. Raman spectroscopy indicated the disappearance of mitochondrial cytochrome signals after thawing. A reduction in the mitochondrial membrane potential was detected using flow cytometry. The performance indices indicated a decrease in attachment efficiency with an increase in the number of temperature cycles. This decrease was observed in the temperature cycle range above the glass transition temperature of the cryoprotectant. Raman observations captured an increase in the signal intensity of intracellular dimethyl sulfoxide (DMSO) during temperature cycles. Based on these results, we proposed a schematic illustration for cellular responses to temperature fluctuations, suggesting that temperature fluctuations above the glass-transition temperature trigger the movement of DMSO, leading to cytochrome c oxidation, mitochondrial damage, and caspase-mediated cell death. This enhances our understanding of the key events during cryopreservation and informs the development of quality control strategies for hiPSC storage and transport.

Exploring serial crystallography for drug discovery.

Structure-based drug design is highly dependent on the availability of structures of the protein of interest in complex with lead compounds. Ideally, this information can be used to guide the chemical optimization of a compound into a pharmaceutical drug candidate. A limitation of the main structural method used today - conventional X-ray crystallography - is that it only provides structural information about the protein complex in its frozen state. Serial crystallography is a relatively new approach that offers the possibility to study protein structures at room temperature (RT). Here, we explore the use of serial crystallography to determine the structures of the pharmaceutical target, soluble epoxide hydrolase. We introduce a new method to screen for optimal microcrystallization conditions suitable for use in serial crystallography and present a number of RT ligand-bound structures of our target protein. From a comparison between the RT structural data and previously published cryo-temperature structures, we describe an example of a temperature-dependent difference in the ligand-binding mode and observe that flexible loops are better resolved at RT. Finally, we discuss the current limitations and potential future advances of serial crystallography for use within pharmaceutical drug discovery.

Calculation of the heat stabilizer effective parameters depending on its location relative to the pile

Maintaining the soil in a frozen state in a cryolithozone is necessary for preventing the collapse of structures. The most effective technical solution for this is the use of two-phase passive heat stabilizers. Monitoring the state of permafrost soil allows to accept technical decisions that prevent soil thawing. Calculation the effective parameters of such decisions requires mathematical modeling of thermal and hydrodynamic processes. An approach is proposed to effectively compensate the heat flux from the pile on the ground, assuming the location of the heat stabilizer in the same well with the pile or at a slight distance from it. The aim of the work is to calculate the effective parameters of the heat stabilizer depending on its location relative to the pile. The developed mathematical model assumes the five tasks: 1) blowing the above-ground part of the heat stabilizer with air; 2) movement of liquid refrigerant to the bottom of the heat stabilizer; 3) cooling of the casing of the heat stabilizer with an two-phase flow of refrigerant; 4) heat exchange in the system refrigerant — the casing — frozen soil; 5) compensation of heat flow from the pile into the ground with heat flow from the ground into the heat stabilizer. The first problem is solved on the basis of an empirical criterion equation. The second and third tasks are solved using the laws of conservation of mass, momentum and energy. The fourth and fifth tasks involve solving the equation of thermal conductivity. As a result of calculations, the effective parameters of the heat stabilizer were obtained. The minimum lateral dimensions of the heat stabilizer casing have been established to compensate the heat flow from the pile into the ground. The time of freezing front reaching the pile from the heat stabilizer located at a distance of 0.5 m from one of its corners has been determined.

P-138 Effect of biofeedback from the blastocysts on the cumulative pregnancy rate

Abstract Study question The study is to compare cumulative pregnancy rates of embryos transferred with and without spent culture media to confront biofeedback’s role in clinical outcomes Summary answer Transferring the blastocysts with spent culture media improved the pregnancy rates. Biofeedback was observed from the blastocyst stage. The blastocyst freezing and transfer approach improved. What is known already Biofeedback is often encountered in regulating menstrual cycles and other events in continuing gestations with estrogen, progesterone, beta hCG..etc. A similar biofeedback is possible with growing blastocyst for implantation. Since the in-vitro culture of embryos is devoid of its occurrence, it may lead to asynchrony of subsequent events and implantation. There is no scientific evidence from metabolomics on the characterization of these substances or secretions from spent culture medium that includes cell-free DNA giving feedback and its role in improving clinical outcomes. Study design, size, duration This retrospective multi-centric study included the 3591 frozen embryo transfers from 1st Apr 2022 to 31st Nov 2023 out of 4623 women who underwent oocyte retrieval from 1st Jan 2022. Patients were divided into study (group A) and control (group B). In group A, 1035 women received the transfers from spent culture media; in group B, 2556 women received transfers after shifting the blastocysts to fresh culture media before loading into the ET catheter. Participants/materials, setting, methods All the transfers considered in this study were day-5 blastocysts, irrespective of their frozen state. Day-5 frozen-thawed were incubated short-time (∼1 hour) before the transfer. Whereas, the frozen embryos and morulas were cultured till day 5. In the study group, all cultures were conducted in 100ul of culture media under oil per embryo to maintain consistency amongst the group. The rest of the laboratory and clinical procedures were consistent between the two groups. Main results and the role of chance The cumulative pregnancy rate was significantly higher in group A than in group B (60.9% Vs 55.6%; OR = 1.23; 95% CI, 1.07 -1.44, Z-score 2.901, P < 0.003). The effect of spent culture media was further observed by regrouping the day-3 or 4 frozen (group A1) and day-5 frozen patients (group A2). Day-5 thawed blastocysts transferred after short incubation to allow the secretions to directly deposit on the endometrium. Group A1 might have a high concentration of secretions due to its accumulation from the embryo or morula stages. Pregnancy rates in group A1 were higher than A2 but not statistically significant (61.7% Vs 59.7%; OR = 1.08, 95% CI, 0.84-1.4, Z-score 0.654, P = 0.51). The less impact indicates that the feedback came from blastocysts rather than embryos. Limitations, reasons for caution It is not evident how these secretions contribute to biofeedback. Quantification, identifying their time of release and recovery from the qualitative tests for their therapeutic use are the limitations. Nevertheless, spent media can be employed if found beneficial. Wider implications of the findings We have taken a large possible data set for control against the test group and took cumulative pregnancy rate as the primary outcome indicator to prove biofeedback from blastocysts can improve the clinical outcomes irrespective of the age and other factors of infertility. Trial registration number Not applicable

Enhancing food preservation and safety: Synergistic effects of Allium-derived organosulfur compounds and outer membrane permeabilization peptide L-11

Ready-to-eat (RTE) foods, characterized by the lack of a terminal heating step prior to consumption, offer enhanced organoleptic qualities compared to their cooked counterparts, as they retain more of their natural flavors, textures, and nutritional content. However, these untreated products pose a risk for foodborne illnesses if not promptly consumed and/or adequately stored under refrigeration or in a frozen state. This investigation delves into the synergistic antimicrobial effects of a novel human-mimetic peptide, L-11, in conjunction with organosulfur compounds derived from Allium species—namely allicin, diallyl sulfide (DAS), dipropyl sulfide (DPS), propyl propane thiosulfinate (PTS), and propyl propane thiosulfonate (PTSO)—on the inhibition and control of Gram-negative foodborne pathogens across various food matrices. Notably, despite the minimal individual antimicrobial activity of peptide L-11 and the evaluated organosulfur compounds against target bacteria (Escherichia coli, Salmonella enterica, Yersinia enterocolitica, and Shigella sonnei), their combinations exhibited remarkable synergistic effects in vitro with until 32-fold reduction for some combinations. Specifically, combinations including PTS and PTSO demonstrated up to a 99% reduction in bacterial proliferation within RTE food models such as salmorejo, aioli, pumpkin cream, and spinach cream. These findings highlight the potential applications of these synergistic combinations in extending the shelf-life and enhancing the safety of RTE foods. To the best of our knowledge, this represents the inaugural report of such synergistic interactions between organosulfur compounds and peptides in extending the shelf-life of RTE foods.

Development of an LC-HRMS/MS Method for Quantifying Steroids and Thyroid Hormones in Capillary Blood: A Potential Tool for Assessing Relative Energy Deficiency in Sport (RED-S).

Relative energy deficiency in sport (RED-S) is a condition that arises from persistent low energy availability (LEA), which affects the hypothalamic-pituitary axis and results in alterations of several hormones in both male and female athletes. As frequent blood hormone status determinations using venipuncture are rare in sports practice, microsampling offers promising possibilities for preventing and assessing RED-S. Therefore, this study aimed at developing a liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS) method for quantifying relevant steroids and thyroid hormones in 30 μL of capillary blood obtained using Mitra® devices with volumetric absorptive microsampling technology (VAMS®). The results of the study showed that all validation criteria were met, including a storage stability of more than 28 days in a frozen state (-18 °C) and 14 days at room temperature (20 °C). The validated assay provided precise (<12%) and accurate (<13%) results for all the target analytes. Furthermore, as a proof of concept, autonomously collected VAMS® samples from 50 female and male, healthy, active adults were analyzed. The sensitivity of all analytes was adequate to quantify the decreased hormone concentrations in the RED-S state, as all authentic samples could be measured accordingly. These findings suggest that self-collected VAMS® samples offer a practical opportunity for regular hormone measurements in athletes and can be used for early RED-S assessment and progress monitoring during RED-S recovery.

A quantitative analysis of stored frozen surplus embryos in the UK

The number of surplus frozen human embryos in storage in the United Kingdom (UK) is at its highest level since records began in 1991 and the formation of the UK Human Fertilisation and Embryology Authority (HFEA). This study features a quantitative analysis of data from 1991 to 2019 provided by the HFEA as well as a commentary on observed trends within this data. We also discuss trends relating to the final destiny of surplus embryos. Data analysis show that at least 130,000 stored embryos have been discarded in the UK since 1991, while another 500,000 embryos are currently being stored in a frozen state, of which a significant proportion is likely to be discarded in the future. However, this creates a moral dilemma since UK legislation relating to human embryos is based on the 1984 Warnock Report which recognizes that they have a special moral status.

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.

Clinical Validation of a Machine-Learned, Point-of-Care System to IDENTIFY Functionally Significant Coronary Artery Disease.

Many clinical studies have shown wide performance variation in tests to identify coronary artery disease (CAD). Coronary computed tomography angiography (CCTA) has been identified as an effective rule-out test but is not widely available in the USA, particularly so in rural areas. Patients in rural areas are underserved in the healthcare system as compared to urban areas, rendering it a priority population to target with highly accessible diagnostics. We previously developed a machine-learned algorithm to identify the presence of CAD (defined by functional significance) in patients with symptoms without the use of radiation or stress. The algorithm requires 215 s temporally synchronized photoplethysmographic and orthogonal voltage gradient signals acquired at rest. The purpose of the present work is to validate the performance of the algorithm in a frozen state (i.e., no retraining) in a large, blinded dataset from the IDENTIFY trial. IDENTIFY is a multicenter, selectively blinded, non-randomized, prospective, repository study to acquire signals with paired metadata from subjects with symptoms indicative of CAD within seven days prior to either left heart catheterization or CCTA. The algorithm's sensitivity and specificity were validated using a set of unseen patient signals (n = 1816). Pre-specified endpoints were chosen to demonstrate a rule-out performance comparable to CCTA. The ROC-AUC in the validation set was 0.80 (95% CI: 0.78-0.82). This performance was maintained in both male and female subgroups. At the pre-specified cut point, the sensitivity was 0.85 (95% CI: 0.82-0.88), and the specificity was 0.58 (95% CI: 0.54-0.62), passing the pre-specified endpoints. Assuming a 4% disease prevalence, the NPV was 0.99. Algorithm performance is comparable to tertiary center testing using CCTA. Selection of a suitable cut-point results in the same sensitivity and specificity performance in females as in males. Therefore, a medical device embedding this algorithm may address an unmet need for a non-invasive, front-line point-of-care test for CAD (without any radiation or stress), thus offering significant benefits to the patient, physician, and healthcare system.

Freeze-sonication delamination method of high crystalline-quality MXene with high yield

MXene has attracted broad attention for its unique physicochemical properties and has flourished in many research areas. Since MXene obtained by high crystalline-quality MAX phase has excellent stability and properties, the etching of high crystalline-quality MAX phase and delamination into monolayer will become an inevitable trend. However, the delamination of the high crystalline-quality MXene is significantly more challenging than conventional MXene because of the more vital van der Waals forces of the more regular interlayer structure. Here, we propose a freeze-sonication delamination (FSD) strategy that can solve the difficult problem of efficiently exfoliation of high crystalline-quality MXene. The principle is to utilize the synergistic effect of ultrasound and ionic intercalation to allow a large number of water molecules to penetrate into the interlayer, which results in volume expansion, and then ultrasound to obtain monolayer MXene in a frozen state. This method not only increases the yield of high crystalline-quality monolayer MXene but also prevents the size reduction and the nanosheet destruction. The yield of monolayer MXene reached 74.2 % with a concentration of 19.8 mg/mL after six FSD cycles (the time of ultrasound treatment is 5 min after per freeze). Meanwhile, under the protection of ice, the obtained monolayer MXene has a larger size with more complete nanosheets than ultrasound-delaminated MXene. Supercapacitors made of high crystalline-quality MXene exhibits excellent gravimetric capacitance of 261.1 F/g and satisfactory cycling stability.

Quantification of Residual Water in Pharmaceutical Frozen Solutions Via 1H Solid-State NMR

Freezing is essential for the stability of biological drug substances and products, particularly in frozen solution formulations and during the primary drying of lyophilized preparations. However, the unfrozen segment within the frozen matrix can alter solute concentration, ionic strength, and stabilizer crystallization, posing risks of increased biophysical instability and faster chemical degradation. While quantifying the unfrozen water content is important for designing stable biopharmaceuticals, there is a lack of analytical techniques for in situ quantitative measurements. In this study, we introduce a 1H magic angle spinning NMR technique to identify the freezing point (Tice) and quantify mobile water content in frozen biologics, applying this method to analyze the freezing of a commercial high-concentration drug product, Dupixent®. Our results demonstrate that water freezing is influenced by buffer salt properties and formulation composition, including the presence of sugar cryoprotectants and protein concentration. Additionally, the 1H chemical shift can probe pH in the unfrozen phase, potentially predicting the microenvironmental acidity in the frozen state. Our proposed methodology provides fresh insights into the analysis of freeze-concentrated solutions, enhancing our understanding of the stability of frozen and lyophilized biopharmaceuticals.

Kinetic glass transition in granular gases and nonlinear molecular fluids.

In this paper, we investigate, both analytically and numerically, the emergence of a kinetic glass transition in two different model systems: a uniformly heated granular gas and a molecular fluid with nonlinear drag. Despite the profound differences between these two physical systems, their behavior in thermal cycles share strong similarities, which stem from the relaxation time diverging algebraically at low temperatures for both systems. When the driving intensity--for the granular gas-or the bath temperature-for the molecular fluid-is decreased to sufficiently low values, the kinetic temperature of both systems becomes "frozen" at a value that depends on the cooling rate through a power law with the same exponent. Interestingly, this frozen glassy state is universal in the following sense: for a suitable rescaling of the relevant variables, its velocity distribution function becomes independent of the cooling rate. Upon reheating, i.e., when either the driving intensity or the bath temperature is increased from this frozen state, hysteresis cycles arise and the apparent heat capacity displays a maximum. The numerical results obtained from the simulations are well described by a perturbative approach.

State diagrams of green peas (Pisum sativum L.) powders with different maltodextrin additions.

The purpose of this study was to examine the effect of maltodextrin addition on the physical stability of powdered green peas. The evaluation of the physical state of the material was based on the equilibrium water content of the monolayer (Xm) and the glass transition temperatures of the powders at room temperature (Tg) and in the frozen state (Tg'). Graphical sorption characteristic at 25°C was determined using static-gravimetric method while capacity of the monolayer values was calculated from the mathematical GAB model. Differential scanning calorimetry was carried out in order to determine glass transition lines and freezing curves which combine together were used to plot state diagrams. Relationship between Tg and solid content were shown by using Gordon-Taylor model. Freezing data were modeled employing the Clausius-Clapeyron equation and its development-Chen model. Sorption isotherms showed sigmoidal shape characteristic for high-molecular weight materials. Monolayer moisture content varied between 0.047 and 0.106 g water/g solids. The glass transition temperature of anhydrous green peas increased in from 89.9 to 175.6°C while Tg' value changed from -43.4 to -26.6°C to as a result of 75% polysaccharide addition. The ultimate maximum-freeze-concentration conditions of the powders were observed in range from 0.783 to 0.814 g solids/g sample. Monolayer capacity, Tg and Tg' values increased with increasing maltodextrin amount in the sample which indicates that the addition of starch hydrolysate has a beneficial effect on the stability of powders stored frozen and at room temperature.

Analysis of strength characteristics of loess before and after freezing using a hollow cylinder torsional shear apparatus

This paper aims to comprehensively analyze the influence of the principal stress angle rotation and intermediate principal stress on loess's strength and deformation characteristics. A hollow cylinder torsional shear apparatus was utilized to conduct tests on remolded samples under both normal and frozen conditions to investigate the mechanical properties and deformation behavior of loess under complex stress conditions. The results indicate significant differences in the internal changes of soil particles, unfrozen water, and relative positions in soil samples under normal and frozen conditions, leading to noticeable variations in strength and strain development. In frozen state, loess experiences primarily compressive failure with a slow growth of cracks, while at normal temperature, it predominantly exhibits shear failure. With the increase in the principal stress angle, the deformation patterns of the soil samples under different conditions become essentially consistent, gradually transitioning from compression to extension, accompanied by a reduction in axial strength. The gradual increase in the principal stress axis angle (α) reduces the strength of the generalized shear stress and shear strain curves. Under an increasing α, frozen soil exhibits strain-hardening characteristics, with the maximum shear strength occurring at α = 45°. The intermediate principal stress coefficient (b) also significantly impacts the strength of frozen soil, with an increasing b resulting in a gradual decrease in generalized shear stress strength. This study provides a reference for comprehensively exploring the mechanical properties of soil under traffic load and a reliable theoretical basis for the design and maintenance of roadbeds.