Freezing Rate Research Articles

Fabrication of Uniform Melatonin Microparticles Potentially for Nasal Delivery: A Comparison of Spray Drying and Spray Freeze Drying.

Insomnia is a major health concern, and melatonin (MLT) is key for initiating sleep. Delivering MLT nasally can enhance brain bioavailability by targeting the olfactory region. This study aimed to fabricate MLT embedded microparticles for nasal delivery. MLT-cyclodextrin (CD) derivatives complex microparticles (MCCMPs) were fabricated by spray drying and spray freeze drying MLT and CD derivative solutions. Phase solubility and 1H-1H ROSEY NMR analysis assessed MLT-CD assembly. The effects of formulation compositions and process parameters on microparticle structural attributes were investigated. The in vitro nasal release and deposition performances were evaluated by a modified paddle-over-disk apparatus and 3D-printed nasal cavity cast, respectively. Sodium sulphobutylether-β-cyclodextrin (SBE-β-CD) exhibited the best complexation ability with MLT, with the indole structure of MLT included in its cavity. Spray dried MCCMPs showed dense structure with high density, while the spray freeze dried counterpart showed the brittle and porous structure with low density. Despite the porous structure may promote the release rate of spray freeze dried samples, the high hydrophilicity of the CD derivative overshadows this advantage. Samples prepared by spray drying not only exhibited rapid release rates but also could deposit more effectively in the olfactory region, as they avoid breakage due to their higher mechanical strength. The optimal sample showed ~ 86.70% of the MLT released at 20min and ~ 10.57% of the deposition fraction in the olfactory region. This work compares MCCMPs fabricated by spray drying and spray freeze drying, providing the optimal formulation and process combinations.

How to infer ocean freezing rates on icy satellites from measurements of ice thickness

Abstract Liquid-water oceans likely underlie the ice shells of Europa and Enceladus, but ocean properties are challenging to measure due to the overlying ice. Here, we consider gravity-driven flow of the ice shells of icy satellites and relate this to ocean freeze and melt rates. We employ a first-principles approach applicable to conductive ice shells in a Cartesian geometry. We derive a scaling law under which ocean freeze/melt rates can be estimated from shell-thickness measurements. Under a steady-state assumption, ocean freeze/melt rates can be inferred from measurements of ice thickness, given a basal viscosity. Depending on a characteristic thickness scale and basal viscosity, characteristic freeze/melt rates range from around O(10−1) to O(10−5) mm/year. Our scaling is validated with ice-penetrating radar measurements of ice thickness and modelled snow accumulation for Roosevelt Island, Antarctica. Our model, coupled with observations of shell thickness, could help estimate the magnitudes of ocean freeze/melt rates on icy satellites.

Comparative study of statistical computational approaches to investigate the degraded compressive strength of concrete under the freeze-thaw effect

The primary cause of frost damage and early failure in concrete structures is the repeated freezing and thaw cycles (FTC). The evolution of internal fractures and scaling at the surface of concrete can be used to assess the impact of frost damage. Surface scaling mechanisms and interior frost damage are contingent upon numerous environmental factors, including the rate of freezing, low temperature, and duration of the freezing point. However, evaluating the amount of strength loss of concrete material is a challenging factor to consider. This work explores the application of predictive modelling tools, including random forest (RF), multilayer perceptron (MLP), decision tree (DT), and bagging, to evaluate the degraded compressive strength (D-CS) of concrete. The models use five input variables: initial compressive strength (I-CS), water-to-cement ratio (W/C), FTC, minimum temperature (Tmin), and maximum temperature (Tmax), with D-CS as the output. Model performance was compared using mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R²) metrics, with the bagging model achieving the highest predictive performance at 92 %. A 10-fold cross-validation approach validated the model's accuracy. The influence of each variable was assessed using SHapley Additive exPlanations (SHAP) analysis. Importantly, a user-friendly Graphical User Interface (GUI) was developed based on the models, making it easy for researchers and professionals to make predictions and thereby increasing the practicality and accessibility of this research. This study aids the research community in selecting appropriate models to forecast the strength of various concrete types, thereby enhancing the practical application of this research.

Quality and microstructure of tilapia fillets (Oreochromis niloticus) subjected to different freezing methods

The Nile tilapia (Oreochromis niloticus) fillets were frozen with static air (SA) at -20 °C, air blast freezing (AF) at -25 °C, combined method (CM - immersion in liquid nitrogen followed by AF) and cryogenic freezing (CF - immersion in liquid nitrogen). The effects of different freezing methods and of storage time at -18 °C (0, 30, 60 and 90 days) on fillet quality were evaluated. The temperature records were obtained, and the freezing times were determined by monitoring the temperatures of the geometric centers of the fillets. For CF, CM, AF and SA, the freezing times were 5.32, 127, 146 and 268 min, respectively. The quality of the frozen fillets was evaluated by measuring pH, volatile nitrogenous bases (TBV-N), thiobarbituric acid reactive substances (TBARS), and fatty acids and by obtaining a texture profile and performing scanning electron microscopy (SEM). The samples frozen by CF, after storage, had the highest levels of TBV-N because the high freezing rate produced superficial cracks that negatively affected the quality of the fillets. Freezing the samples with SA produced the worst quality indices and the microstructure was visibly damaged, with greater spaces between the fibers left by ice crystals. For all parameters evaluated, freezing with AF and CM resulted in fast freezing rates and better-quality tilapia fillets for 90 days of storage.

Insight into quality, microstructure, and protein physicochemical properties of Monopterus albus frozen with liquid nitrogen

Monopterus albus is highly susceptible to spoilage due to high protein and moisture contents while frozen storage can effectively prolong the shelf-life. To study the effect of liquid nitrogen freezing (LNF) on quality, microstructure of ice crystal and muscle fiber, and physicochemical properties of proteins, Monopterus albus was frozen at -20 °C by refrigerator (RF, control), -50 °C, -80 °C, and -110 °C by LNF, respectively. The -110 °C LNF exhibited the highest freezing rate among four groups, contributing to the formation of small ice crystals with more uniform distribution and alleviating the damage to muscle fiber. In -110 °C LNF group, protein secondary structure changed relatively subtle, resulting in high protein solubility, Ca2+-ATPase activity, and total sulfhydryl content, as well as low surface hydrophobicity and disulfide bond content. LNF retarded the rise of TVB-N value, prevented the loss of immobilized and free water, and maintained water holding capacity and shear force. In conclusion, -110 °C LNF was recommended a promising freezing process for frozen Monopterus albus due to less alteration of quality and alleviation of protein denaturation.

Effects of vegetation extreme degradation on soil hydrothermal processes in alpine wet meadow on the central Qinghai–Tibet Plateau

Ongoing climate warming and humidification have triggered a series of environmental responses, including vegetation succession, significant permafrost degradation, hydrological shifts, alterations in water resources, and increased frequency of freeze-thaw events. Notably, vegetation modulates the water cycle, regulates soil temperatures, and sustains permafrost stability. However, the extent to which the degradation of alpine vegetation impacts soil hydrothermal processes in permafrost regions is unclear. Therefore, we measured the soil moisture and temperature of the alpine wet meadow (AWM) and extremely degraded alpine wet meadow (EDAWM) ecosystems within the permafrost regions of the Qinghai–Tibet Plateau in situ. The objectives of this study were to explore the freeze-thaw cycles and hydrothermal dynamics within the active layer and to understand the mechanisms behind the effects of extreme alpine vegetation degradation. The results revealed that the AWM ecosystem had a longer soil freezing duration and a higher soil freezing rate than those of the EDAWM ecosystem. Additionally, the freezing index was higher in EDAWM than that in AWM, while differences in the thawing index were insignificant. The variance in the thaw-freeze ratios between the two ecosystems indicated that extreme vegetation degradation in AWM altered soil heat absorption and dissipation in the plant root zone and the deeper active layer. Moreover, EDAWM exhibited a decrease in soil bidirectional freezing processes, particularly from the permafrost table upwards. The extreme degradation in AWM changed soil physical properties and organic matter content, reducing ground temperatures in the active and permafrost layers of EDAWM, particularly during winter. The reduced heat transfer in EDAWM resulted in an active layer depth 9 cm shallower than that in AWM. Without vegetation cover, soil moisture in EDAWM was more prone to evaporation or deeper infiltration, leading to lower soil moisture content than that in AWM. Furthermore, an increase in soil moisture content decreased temperature in shallow soils in AWM but increased it in shallow soils in EDAWM. In summary, extreme vegetation degradation impaired air-heat exchange in AWM soil. These insights provide a scientific and theoretical basis for predicting permafrost evolution in the Qinghai–Tibet Plateau, highlighting the complex interactions among vegetation degradation, soil hydrothermal processes, and climatic factors.

Formation Rate and Energy Efficiency of Ice Plug in Pipelines Driven by the Cascade Utilization of Cold Energy

Ice plug technology is an effective method for isolating the pipeline system, which are promising methods utilized in the nuclear, chemical, and power industries. To reduce the cold energy consumption and temperature stress, the multi-stage (1–10) of time-dependent thermal boundary conditions was proposed for the formation of ice plug, while the gradient cooling wall temperature of multi-stage was applied. A numerical model considering the liquid–solid phase change, heat transfer, and time-dependent thermal boundary condition has been established. The effects of the ratio of length and diameter of the cooling wall lc/d (1–9) on the formation rate and heat flux of ice plug in the pipe has been investigated. The fastest formation rate of ice plug with 800 mm in the axial direction (7.47 cm3/s) was observed in the pipe with the lc/d of 5. The formation rate of ice plug and the ice formation volume under unit energy consumption VE under various stages (1–10) of cooling wall temperature have been compared. The VE of eight temperature stages (1.45 cm3/kJ) was 1.16 times than the VE of one temperature stage, which satisfied the freezing rate at the same time. This investigation provides insight for proposing an energy-saving system for the formation of ice plug.

A vasculature based nanocryosurgical model for tumor destruction

The vascular model built on porous media approach is a more realistic representation of biological tissue. A vasculature system based axisymmetric cryosurgical model is proposed here for cryosurgery of lung tumor based on the freezing of the vascular region of the biological tissue. A two-temperature model is developed based on the porous medium approach considering the thermal non-equilibrium between the tissue and the blood region. Bioheat transfer phenomenon between tissue and blood involves interfacial heat transfer, perfusion heat transfer and metabolic heat generation in tissue cylinder. To improve the cryothermal penetration inside the tumor tissue, high conductive nanoparticles are injected into it which increases the local freezing rate of tumor region with minimum damage to the surrounding healthy tissue. The blood phase change in the vascular network is modelled through a source based implicit enthalpy method. The proposed model is utilized to simulate cryosurgery for lung lesion. It is observed that the solidification time for 99.9% tumor using Pennes model and Vascular model (ε=0.01) are 414 s and 512 s respectively, which shows that Pennes model overpredicts the freezing of tumor during cryosurgery. The freezing necrosis is found to reduce by 13.95% at 0.05 (volume fraction) nanoparticle concentration.

A computational study of binary eutectic system with convection under volumetric freezing: A Moving Boundary Problem

A reduction in the operating time during the solidification of an eutectic alloy is one of the prime demands in front of the investigators. The classical theory of solidification was not able to offer rapid solidification of an alloy due to not account the structural property of the material. To account convection and external heat sink effect, an external volumetric heat sink is considered and it depends on the distance and time. The thermal conductivity, density, and specific heat of the mushy zone are assumed to be the linear combination of solid and liquid regions properties with a solid fraction distribution. The mathematical model accounts for the solid fraction distribution, which has a linear relationship with the temperature of the mushy zone. The analytical solution of the problem has been determined via similarity transformation. To explore the current study, numerical data of the Copper-Aluminum alloy with 5% Copper is presented. It has been found that with a volumetric heat sink, the rate of solidification becomes faster than usual. Further, the rate of heat removal from the surface accelerates. Convection enhances the rate of freezing of the eutectic alloy. The temperature of the mushy region is going up for the increasing value of the solid fraction in mushy zone, which is lying in [0,1] and when we increase the strength of volumetric heat, then the temperature profile decreases and, the first-interface and second-interface increase gradually in the whole medium. We compared the current result with Tien and Geiger’s result, and it is found in good compliance. It is expected that the current study will improve the fundamental understanding of the solidification of an eutectic alloy and reduce the time for freezing, which is useful to design industrial freezing devices for alloys.

Cryopreservation of human semen by inherently-controlled icing probability: Or how the surface profile of superhydrophobic carbon soot coatings and the sperm volume affect the outcome of slow freezing?

The restoration of initial functionality of human spermatozoa subjected to cryopreservation is challenging, because the deleterious intracellular icing and the occurrence of osmotic shocks due to prolonged exposure to increased concentrations of intracellular solutes are oppositely dependent on the cooling rate. This longstanding problem could be overcome if using superhydrophobic soot coatings delaying the heat transfer rate, reducing the ice formation probability and triggering balanced and timely dehydration of the cells, but the effect of their surface profile and sperm volume on the success rate of slow freezing is unclear. Here, we show for the first time that the two-factor freezing injury is entirely avoidable by tailoring the solid-to-gas voids (pores) fraction in the soot, leading to increased nucleation free energy barrier, presumable incipiency of ice crystals with controllable shape and size and hence, fully (100 %) recovered post-thaw sperm motility. It is demonstrated that the reason for such a unique scientific result is the selection of soot coatings with appropriate morphochemical features, hypothetically (not directly proven yet) inducing equilibrium among the solution composition and ice crystals formation, retarding the undesirable compression of liquid-filled “slush ice” channels surrounding the cytoplasm and impeding the ice recrystallization. The novel insights introduced in this article open endless horizon for customizing and revolutionizing the technical protocols in cryobiology.

Downscaling platelet cryopreservation: Are platelets frozen in tubes comparable to standard cryopreserved platelets?

Platelet cryopreservation extends the shelf-life to at least 2 years. However, platelets are altered during the freeze/thaw process. Downscaling platelet cryopreservation by freezing in tubes would enable rapid screening of novel strategies to improve the quality of cryopreserved platelets (CPPs). The aim of this study was to characterize the effect of freezing conditions on the in vitro phenotype and function of platelets frozen in a low volume compared to standard CPPs. Platelets were prepared for cryopreservation using 5%-6% DMSO and processed using standard protocols or aliquoted into 2 mL tubes. Platelets were hyperconcentrated to 25 mL (standard CPPs) or 200 μL (tubes) before freezing at -80°C (n = 8). Six insulators/controlled rate freezing containers were used to vary the freezing rate of platelets in tubes. Platelets were thawed, resuspended in plasma, and then assessed by flow cytometry and thromboelastography. The use of different insulators for tubes changed the freezing rate of platelets compared to platelets frozen using the standard protocol (p < .001). However, this had no impact on the recovery of the platelets (p = .87) or the proportion of platelets expressing GPIbα (p = .46) or GPVI (p = .07), which remained similar between groups. A lower proportion of platelets frozen in tubes externalized phosphatidylserine compared to standard CPPs (p < .001). The clot-forming ability (thromboelastography) of platelets was similar between groups (p > .05). Freezing platelets in tubes modified the freezing rate and altered some platelet characteristics. However, the functional characteristics remained comparable, demonstrating the feasibility of downscaling platelet cryopreservation for high-throughput exploratory investigations.

Hydro-thermal-solid modeling of artificial ground freezing through cold gas convection

The inrush of groundwater impairs heating efficiency during oil shale in situ pyrolysis mining, and it also increases oily waste-water production. Artificial ground freezing (AGF) is an ideal method to block the adverse groundwater infiltration, while the poor freezing performance and high energy consumption of the current AGF pattern are the biggest obstacles, even failing at high-velocity seepage flow. This study proposed and investigated a novel pattern of AGF through cold gas convection (GC) for oil shale in situ reservoir, this pattern have the potential to enhance the freezing performances, especially when encounters the high-velocity seepage flow. In this study, a coupled hydro-thermal-solid model was developed and numerical simulations were performed, the enhancement mechanism of freezing performances and energy conversion have been analyzed to reveal the superiority of the GC-AGF. The results indicated that the maximum freezing rates were twice the current AGF. With seepage flow, the shape of the frozen zone developed elliptically perpendicular to the seepage flow direction, and the effective radius of the frozen zone formed by GC-AGF decreased only by 10%–20 %, even at a higher-velocity seepage flow. The analysis showed that the gas-water two-phase zone was a barrier to the direct heat exchange between the infiltrated groundwater and the frozen zone, which was the enhancement mechanism of GC-AGF. Correspondingly, the specific energy consumption reduced from 8.0 × 107 to 3.8 × 107 J/m at a higher-velocity seepage flow. The results showed that the proposed GC-AGF method significantly enhanced the freezing performance with low energy consumption.

Adhesion of impure ice on surfaces.

The undesirable buildup of ice can compromise the operational safety of ships in the Arctic to high-flying airplanes, thereby having a detrimental impact on modern life in cold climates. The obstinately strong adhesion between ice and most functional surfaces makes ice removal an energetically expensive and dangerous affair. Hence, over the past few decades, substantial efforts have been directed toward the development of passive ice-shedding surfaces. Conventionally, such research on ice adhesion has almost always been based on ice solidified from pure water. However, in all practical situations, freezing water has dissolved contaminants; ice adhesion studies of which have remained elusive thus far. Here, we cast light on the fundamental role played by various impurities (salt, surfactant, and solvent) commonly found in natural water bodies on the adhesion of ice on common structural materials. We elucidate how varying freezing temperature & contaminant concentration can significantly alter the resultant ice adhesion strength making it either super-slippery or fiercely adherent. The entrapment of impurities in ice changes with the rate of freezing and ensuing adhesion strength increases as the cooling temperature decreases. We discuss the possible role played by the in situ generated solute enriched liquid layer and the nanometric water-like disordered ice layer sandwiched between ice and the substrate behind these observations. Our work provides useful insights into the elementary nature of impure water-to-ice transformation and contributes to the knowledge base of various natural phenomena and rational design of a broad spectrum of anti-icing technologies for transportation, infrastructure, and energy systems.

Static magnetic field can ameliorate detrimental effects of cryopreservation on human spermatozoa.

This study aims to improve the freezing-thawing process of human sperm using a static magnetic field. The study included 25 normozoospermic human samples. After an initial evaluation of sperm parameters, samples were prepared by the direct swim-up method. Before freezing, sperm motility, viability, morphology, acrosome reaction and DNA fragmentation rate were assessed. The samples were divided into 4 groups: 0, 1, 5 and 10 mT, and each group was frozen by the rapid freezing method. After thawing, the parameters were re-evaluated and compared between groups. Sperm motility decreased significantly during cryopreservation in all groups. The static magnetic field did not protect against decreased progressive motility after freezing, but the total sperm motility was significantly higher in the 10 mT group compared to the other groups. Sperm viability was higher in the 10 mT group than in the other groups. There was no significant difference in the rate of normal sperm morphology after freezing. The rate of spermatozoa with intact acrosome decreased after freeze-thawing, and the static magnetic field did not protect against the acrosome reaction. The rate of DNA integrity was significantly higher in the 10 mT group compared to the other groups. A static magnetic field with an intensity of 10 mT improved sperm viability and DNA integrity compared to other groups. However, it did not provide significant protection against decreased sperm motility or acrosome reaction.

CONGELAREA CRIOGENICĂ A UNOR SPECII DE FRUCTE DE PĂDURE UTILIZÂND UN MODEL EXPERIMENTAL DE ECHIPAMENT MULTIFUNCȚIONAL DE CONGELARE RAPIDĂ

For the preservation of horticultural products, the best results in keeping the attributes and quality at a level as close as possible to that of the fresh product are obtained when artificial cold (refrigeration, freezing) is used, unlike other methods. Among the existing freezing methods, freezing with cryogenic agents allows obtaining average linear freezing rates superior to the other methods. The fastest procedure for cooling food products involves the use of liquid nitrogen, which comes into direct contact with the surface of the food product that needs to be frozen. The paper analyzes the quick freezing process of three species of berries, namely blueberries, strawberries and raspberries, using an experimental model of multifunctional quick-freezing equipment - ICR, developed by INMA Bucharest as part of a national research programme. Total times and average linear freezing rates, as well as liquid nitrogen consumptions for each of the three species subjected to freezing, were tracked. Following the analysis of the experimental data, there were found the following: the minimum total freezing time, 498 s, was recorded for blueberries and the maximum total freezing time, 773 s, was recorded for strawberries; for blueberries and strawberries the average linear freezing rates recorded values of 6.32 cm/h and 6.29 cm/h corresponding to a very fast freezing process and for raspberries the average linear freezing rate recorded a value of 1.62 cm/h corresponding to a fast freezing process; liquid nitrogen consumption recorded a minimum value of 6.90 kg for blueberries and a maximum value of 7.20 kg for raspberries. In the case of blueberries, at the end of the freezing process, cracks and fissures of the epidermis and pulp were observed as a result of the thermal shock induced during the very rapid freezing process.

Controlling the rate of discharging by loading nanoparticles incorporating numerical method in presence of water within the storage enclosure

In this groundbreaking study, an adaptive grid approach was harnessed to simulate the unsteady phenomena of freezing within a complex enclosure, employing an implicit approach. The equations were streamlined by disregarding velocity impact, and two critical equations were addressed using the Finite Element Method (FEM). Within the enclosure, innovative tree-shaped fins were integrated, and the introduction of loaded nano-powders marked a pivotal advancement in accelerating the rate of freezing. Extensive validation of our numerical procedure was conducted, and we systematically examined the influences of “m” and ϕ across various cases. The implementation of a single-phase approximation was pivotal in deriving crucial features. With the dispersion of nanomaterials, we observed a remarkable increase in the penetration of cold regions, resulting in a substantial 26.86 % reduction in completion time. Additionally, the utilization of blade-shaped nano-powders led to a notable 6.98 % decrease in completion time. It is noteworthy that the influence of each variable becomes more pronounced in the presence of higher values of the other parameter. This pioneering approach significantly advances our understanding of solidification processes within complex enclosures utilizing nanoparticles.

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.

Efficacy of nonocclusive separate freezing technique of cryoballoon pulmonary vein isolation: comparison of novel and conventional cryoballoon system

Abstract Background/Introduction Complete occlusion of pulmonary vein (PV) with cryoballoon is an important factor to achieve enough temperature drop and successful pulmonary vein isolation (PVI). However, it is sometimes difficult to occlude PV completely because of large diameter or anatomical difference. Distal cryoblloon positioning in the PV can achieve complete occlusion but it may increase risk of phrenic nerve injury or PV stenosis. Nonocclusive separate freezing technique, freezing superior and inferior portion of the PV at proximal side with no complete occlusion, may be useful for that situation but efficacy of the technique is not well elucidated. Purpose The purpose of this study is to investigate efficacy of nonocclusive separate freezing technique and compare procedure details of the POLARx and the Arctic Front Advance Pro (AFA-Pro). Methods We retrospectively analyzed consecutive patients who underwent cryoballoon ablation with nonocclusive separate freezing technique from September 2019 to February 2023. We defined failure of the nonocclusive separate freezing as the case which needed distal complete occlusion with cryoballoon or touch up radiofrequency ablation to achieve PVI. We analyzed success rate of nonocclusive separate freezing and evaluated nadir temperature, freezing time and number of application times. We also explored incidence of stop of freezing due to phrenic nerve injury (PNI) or esophageal temperature drop during the procedure and permanent PNI and gastroesophageal complications after the procedure between the POLARx and the AFA-Pro. Results One-hundred and one patients, 73 were male (72.3%) and mean age was 66.8 ± 10.5 years, were analyzed. Total PVs were 121 (left superior (LS) PV 31, right superior (RS) PV 53, left common (LC) PV 37) and the POLARx was 45 (LSPV 18, RSPV 24, LCPV 3) and the AFA-Pro was 76 (LSPV 13, RSPV 29, LCPV 34). Success rates of the separate freezing of the POLARx was 84.4% and the AFA-Pro was 77.6% (p=0.48). There were no significant differences in freezing time and number of application times but nadir temperature was significantly lower in the POLARx (-52.1 ± 4.7 °C vs -42.9 ± 7.2 °C, p&amp;lt;0.001). The incidence of stop of freezing had no significant difference between the POLARx and the AFA-Pro but nadir temperature of stop of freezing due to esophageal temperature drop was significantly lower in the POLARx (-53.8 ± 4.3 °C vs -44.7 ± 7.7 °C, p=0.039). Permanent PNI was not seen but two gastric hypomotility events occurred in the POLARx. Conclusions There was no significant difference of success rate of the nonocclusive separate freezing technique but it tended to be higher and nadir temperature was significantly lower in the POLARx. There was no obvious complication in the AFA-Pro but two gastric hypomotility events were seen in the POLARx.

Correlation Between Cued Fear Memory Retrieval and Oscillatory Network Inhibition in the Amygdala Is Disrupted by Acute REM Sleep Deprivation

The basolateral amygdaloid complex (BLA) is critically involved in emotional behaviors, such as aversive memory formation. In particular, fear memory after cued fear conditioning is strongly associated with the BLA, whereas both the BLA and hippocampus are essential for contextual fear memory formation. In the present study, we examined the effects of acute (3 h) sleep deprivation (SD) on BLA-associated fear memory in juvenile (P24-32) rats and performed in vitro electrophysiology using whole-cell patch clamping from the basolateral nucleus (BA) of the BLA. BA projection neurons exhibit the network oscillation, i.e., spontaneous oscillatory bursts of inhibitory transmission at 0.1–3 Hz, as previously reported. In the present study, SD either before or after fear conditioning (FC) disturbed the acquisition of tone-associated fear memory without significant effects on contextual fear memory. FC reduced the power of the oscillatory activity, but SD did not further reduce the oscillation power. Oscillation power was correlated with tone-associated freezing rate (FR) in SD-free fear-conditioned rats, but this relation was disrupted in SD treated group. Rhythm index (RI), the rhythmicity of the oscillation, quantified by autocorrelation analysis, also correlated with tone-associated FR in the combined data, including FC alone and FC with SD. These results suggest that slow network oscillation in the amygdala contributes to the formation of amygdala-dependent fear memory in relation to sleep.

Effects of transient temperature gradient on frost heave of saturated silty clay in an open system

Frost heave in seasonally frozen regions is a one-dimensional process that could severely damage infrastructure subgrades. Stress state, temperature and water migration are important factors for frost heave. This work investigated the effects of soil temperature and volumetric water content on the transient frost heave ratio during the freezing of saturated silty clay in an open system and analyzed the relationships between the transient frost heave ratio and freezing rate and between temperature gradient and frost heave rate. The results show that the frost heave ratio, frost heave rate, and freezing rate are positively correlated with the temperature gradient since the temperature gradient drives the water migration during freezing, indicating the transient temperature gradient could be used to evaluate the frost heave of saturated silty clay. The transient freezing rate and transient frost heave ratio are logarithmically related to the transient frost heave ratio and transient temperature gradient, respectively. The effects of transient temperature gradient on frost heave are the principal mechanism responsible for different frost heave characteristics and uneven frost heave along a subgrade of the same soil type.