Freezing Time Research Articles

Insight into Effects of high Intensity Ultrasound Treatment on Foamability and Physicochemical Properties of Frozen egg White Protein

Frozen storage can greatly improve the shelf life of fresh egg white protein (EWP), but it will also lead to the reduction of protein foaming and can not meet the application needs. Herein, high-intensity ultrasound (HIUS) was used to improve the foam characteristics of EWP in different frozen storage periods. The results showed that compared with fresh egg white, the foaming ability of EWP with different freezing times (0, 3, 7, 14, 21 days) after HIUS treatment (20 kHz, 60% amplitude, 5 min) was significantly improved, especially the EWP after 21 days of frozen storage was doubled by HIUS induction. Furthermore, it was found that the improvement of EWP foamability was mainly due to the enhancement of surface hydrophobicity (H0, the value from 263 to 456) and the decrease of apparent viscosity (from 0.506 Pa.s to 0.007 Pa.s), which increased the diffusion rate of protein to the interface (from 0.19 mNm− 1s− 0.5 to 0.26 mNm− 1s− 0.5) and its adsorption amount (from 35.8 to 43.3%) at the interface. These results showed that HIUS was a simple, efficient and residue free way to improve the foam characteristics of frozen EWP, which has strong promotion and application value.

Strong mechanical and durable superhydrophobic photothermal MWCNTs/SiO2/PDMS/PVDF composite coating for anti-icing and de-icing

A MWCNTs/SiO2/PDMS/PVDF superhydrophobic photothermal composite coating has been prepared by a simple scraping method. The coating can be scraped on different substrates and exhibit excellent superhydrophobic photothermal performance. The obtained superhydrophobic photothermal coating not only has excellent light absorption, acid and alkali resistance, weather resistance and simple preparation process, etc., but also has strong abrasion resistance, adhesion ability and weak light ice-melting performance. The coating still can keep a good superhydrophobic performance after about 80 and 30 abrasion cycles (~40 and 15 m) with about 3.3 and 8.2 kPa pressure on a 360-mesh sandpaper, respectively. Based on the method of Paints and Varnishes-Cross-Cut Test, the adhesion level of the coating can be classified as grade 1. Under 11.5 °C ambient temperature, the coating surface can reach a saturation temperature of around 30 °C with only 0.2 sun irradiation within 5 min. At −15 °C and no light irradiation, compared with the bare aluminum substrates, the coating can delay the freezing time more than twice. At −15 °C, the 0.2 sun irradiation intensity is enough for the coating to prevent 100 μL water droplets from freezing. In contrast, without the coating, the 100 μL water droplet started to freeze after 93 s with 0.2 sun irradiation and it was completely frozen after 285 s. Besides, the ice pellet began to melt after 271 s through the photothermal effect of the coating with low irradiation intensity of 0.2 sun at −15 °C. However, for the same ice pellet, the ice melting cannot occur without photothermal coating under the same conditions. The superhydrophobic photothermal coating shows good application potential in practical engineering.

Impact of preanalytical freezing delay time on the stability of metabolites in oral squamous cell carcinoma tissue samples.

Metabolite stability is critical for tissue metabolomics. However, changes in metabolites in tissues over time from the operating room to the laboratory remain underexplored. In this study, we evaluated the effect of postoperative freezing delay time on the stability of metabolites in normal and oral squamous cell carcinoma (OSCC) tissues. Tumor and paired normal tissues from five OSCC patients were collected after surgical resection, and samples was sequentially quenched in liquid nitrogen at 30, 40, 50, 60, 70, 80, 90 and 120min (80 samples). Untargeted metabolic analysis by liquid chromatography-mass spectrometry/mass spectrometry in positive and negative ion modes was used to identify metabolic changes associated with delayed freezing time. The trends of metabolite changes at 30-120 and 30-60min of delayed freezing were analyzed. 190 metabolites in 36 chemical classes were detected. After delayed freezing for 120min, approximately 20% of the metabolites changed significantly in normal and tumor tissues, and differences in the metabolites were found in normal and tumor tissues. After a delay of 60min, 29 metabolites had changed significantly in normal tissues, and 84 metabolites had changed significantly in tumor tissues. In addition, we constructed three tissue freezing schemes based on the observed variation trends in the metabolites. Delayed freezing of tissue samples has a certain impact on the stability of metabolites. For metabolites with significant changes, we suggest that the freezing time of tissues be reasonably selected according to the freezing schemes and the actual clinical situation.

Determinants of transplantation success with cryopreserved ovarian tissue: data from 196 women of the FertiPROTEKT network.

What are the pregnancy and live birth rates for ovarian tissue transplantation and which factors are associated with the success rate? Pregnancy and live birth rates per transplanted woman are 32.7% and 26.5% and success rate is associated with female age and first versus repeated transplantation. Live birth rates after ovarian tissue transplantations have been reported to be between around 24% and 41% per patient. Success rates seem to be negatively associated with increasing female age at the time of tissue cryopreservation and with pelvic radiation. Success rates are apparently not reduced after overnight transportation of ovarian tissue before freezing. Registry analysis of 244 transplantations in 196 women, performed by 26 FertiPROTEKT network centres from 2007 to 2019 with follow-up till December 2020. Orthotopic ovarian tissue transplantations were performed in 196 women, 191 with previous malignant and 5 with previous non-malignant diseases. Size of transplanting centres varied between 1 and 100 transplantations per centre (median: 2). Factors possibly associated with success rate such as female age, first and repeated transplantation, experience of the transplanting centre and overnight transportation of the ovarian tissue before freezing were analysed. Average age of all 196 transplanted women was 31.3 years (SD 5.2; range 17-44) at the time of cryopreservation of tissue and 35.9 years (SD 4.8; range 23-47) at the time of transplantation. Pregnancy rate was 30.6% (95% CI, 24.2-37.6%) per first transplantation and 32.7% (95% CI, 26.1-39.7%) per patient. Pregnancy rate was higher after first transplantation (30.6% (95% CI, 24.2-37.6%)) compared to second and subsequent transplantations (11.8% (95% CI, 3.3-27.5%)). Live birth rate per first transplantation was 25.0% (95% CI, 19.1-31.7%) and per patient 26.5% (95% CI, 20.5-33.3%). Success rate decreased with increasing age at the time of ovarian tissue freezing. Live birth rate was 28.2% (95% CI, 20.9-36.3%) in women <35 years and 16.7% (95% CI, 7.9-29.3%) in women >35 years. Pregnancy rates after first transplantation were higher in centres who had performed ≥10 transplantations (35.1%) compared to centres with <10 transplantation (25.4%) (P = 0.12). Corresponding live birth rates were 27.0% and 18.6%. Success rates were not different in women with and without overnight transportation of tissue before cryopreservation. The data were drawn from a registry analysis. Data such as ovarian reserve and premature ovarian insufficiency were not available for all women. Data might be influenced by different follow-up policies of the centres. The study reveals the high potential of ovarian tissue freezing and transplantation, but only if freezing is performed in younger women. The study suggests focus should be placed on the first and not on repeated transplantations. It also opens the discussion of whether transplantation should rather be performed by experienced centres. No funding. No competing interests. N/A.

Development of microbiological criteria for evaluating frozen fish based on the amount of psychrotrophic microflora

Unrefrigerated fish and seafood are dominated by mesophilic microflora. At the same time, during their storage in the conditions of refrigerating chambers, a cold-loving – psychrotrophic microbiota dominates, which, according to many scientists, causes organoleptic and chemical changes in fish and affects sanitary and hygienic indicators. Therefore, the microbiological assessment of frozen fish by the content of psychrotrophic microbiota, which participates in its reduced safety and quality, will make it possible to propose preventive measures against spoilage. The aim of the work was to develop a microbiological criterion for the hygiene of the technological process of frozen fish based on the assessment of the content of psychrotrophic microbiota. In the work, standard methods were used, in particular, the microbial number was determined in the samples at a temperature of (30 ± 1) ºС incubation of crops for 72 hours and at a temperature of (6.5 ± 0.5) ºС incubation for 10 days (psychrotrophic microbiota). It was established that during the storage of frozen fish at a temperature of -18 °С, the mesophilic microflora is inactivated, as a result of which its number gradually decreases. However, the intensity of inactivation of mesophilic bacteria in samples with insignificant microbial insemination is, on average, 1.4 times faster, compared to samples with a larger number of microorganisms. In our opinion, this is due to the fact that the composition of mysophilous microflora is largely represented by genera of bacteria that show tolerance to cold. At the same time, the psychrotrophic microflora of frozen fish does not become inactivated during the 8-month storage period at a temperature of -18 °C, and is more stable compared to the mesophilic one. That is, no significant increase or decrease in the number of microorganisms was noted. As a result, by the amount of psychrotrophic microflora of frozen fish, determined at any stage of storage, it is possible to judge its amount at the time of freezing. The amount of psychrotrophic microflora more objectively characterizes the hygienic conditions of production, compliance with the freezing temperature. The microbiological hygiene criteria of the technological process of frozen fish production were substantiated and developed based on the estimation of the amount of psychrotrophic microflora (n = 5; c = 3; m = 10000 CFU/g; M = 50000 CFU/g). These criteria indicate compliance with a set of hygienic measures from freezing to circulation of fish. Therefore, the determined microbiological criterion for the quantity of psychrotrophic microflora in frozen fish complements the existing methods of evaluating the hygiene of the technological process and aims to broadly assess the microbiological safety of frozen fish.

Study on mechanical response and strain of frozen coal after ultra-low temperature

In order to systematically analyze the mechanical response and strain evolution of frozen coal samples after liquid nitrogen (LN2) freezing, based on MTS testing machine to carry out uniaxial compression test. The stress–strain curves of coal samples under different time of LN2 freezing were obtained. The influence mechanism of LN2 freezing on mechanical properties of coal is analyzed. The results show that: (1) With the increase of freezing time and moisture content, the deformation of coal sample decreases under the action of ice cementation, and the closing strain and peak strain decrease. (2) Uniaxial compressive strength, elastic modulus and quality indexes of coal samples decrease with the increase of freezing time and moisture content. (3) The elastic energy of uniaxial loaded coal samples is positively correlated with freezing time and moisture content. (4) Using scanning electron microscopy analysis. After freezing by LN2, fractures in coal samples expand and connect, which result in mechanical properties deterioration. The higher the moisture content and the longer the freezing time, the stronger the deterioration effect of mechanical properties after freezing.

Early life exposure to chronic unpredictable stress induces anxiety-like behaviors and increases the excitability of cerebellar neurons in zebrafish

Anxiety is a common emotional disorder in children. To understand its underlying mechanisms, chronic unpredictable stress (CUS) has been established as a stress model in zebrafish. By using the tall tank test, the stress response reliability could be improved in adult fish which has not been confirmed in larvae. In addition, the increasing evidences have shown that cerebellum plays important roles in anxiety. Whether CUS will affect cerebellar neuronal activity remains unknown. We found that CUS exposure to larvae (from 10 to 17 days post fertilization) induced anxiety-like behaviors and social cohesion impairments within 1–2 d after CUS, including a prolonged freezing time, an increased time spent at the bottom of tank, an increased thigmotaxis index, and an increased interindividual distance. Our results showed that the four behavioral tests were homogeneous, especially the tall tank test either anxiety-like behaviors or the basal locomotion. Furthermore, we found that CUS enhanced the excitability of cerebellar neurons, as the amplitude, frequency, time to peak and half-width of spontaneous firing significantly decreased, as well as the amplitude of excitatory post-synaptic current when compared with the control group. CUS also activated hyperpolarization-activated cyclic nucleotide-gated and potassium channels of cerebellar neurons. Multiple linear regression analysis showed that the total distance in bottom (tall tank test) was correlated positively with outward Na+-K+ currents (r = 0.848, P = 0.016), and the thigmotaxis index (open field test) correlated with action potential amplitude (r = 0.854, P = 0.030). Altogether, early life CUS transiently induced an anxiety-like behavior which could be more accurately assessed by combining the tall tank test with other behavior tests in young zebrafish. CUS increased the excitability of cerebellar neurons might provide new targets to treat emotional diseases such as anxiety.

Integrated Lipidomic and Metabolomics Analysis Revealing the Effects of Frozen Storage Duration on Pork Lipids.

Frozen storage is an important strategy to maintain meat quality for long-term storage and transportation. Lipid oxidation is one of the predominant causes of the deterioration of meat quality during frozen storage. Untargeted lipidomic and targeted metabolomics were employed to comprehensively evaluate the effect of frozen duration on pork lipid profiles and lipid oxidative products including free fatty acids and fatty aldehydes. A total of 688 lipids, 40 fatty acids and 14 aldehydes were successfully screened in a pork sample. We found that ether-linked glycerophospholipids, the predominant type of lipids, gradually decreased during frozen storage. Of these ether-linked glycerophospholipids, ether-linked phosphatidylethanolamine and phosphatidylcholine containing more than one unsaturated bond were greatly influenced by frozen storage, resulting in an increase in free polyunsaturated fatty acids and fatty aldehydes. Among these lipid oxidative products, decanal, cis-11,14-eicosenoic acid and cis-5,8,11,14,17-dicosapentaenoic acid can be considered as potential indicators to calculate the freezing time of unknown frozen pork samples. Moreover, over the three-month frozen storage, the first month was a rapid oxidation stage while the other two months were a slow oxidation stage.

Influence of the pressure shift freezing and thawing on the microstructure of largemouth bass

The objective of this study was to use a new self-cooling laboratory system for carrying out the pressure shift freezing (PSF) and evaluate the influence of PSF at 150 MPa on the microstructural properties of largemouth bass relative to liquid immersion freezing (LIF) and conventional air freezing (CAF). CAF, LIF and PSF showed average total freezing times of 176 ± 7.4, 65.3 ± 6.8 and 23.2 ± 3.1 min, and the cross sectional area of ice crystals in the muscle were 1002 ± 778, 501 ± 248 and 143 ± 50.6 μm2, respectively, demonstrating a significant reduction in crystal size to be associated with PSF. It was observed that damage caused by the ice crystals during the freezing to the muscle microstructure was irreversible. The thawing and cooking losses of largemouth bass after the freezing were lower for PSF as compared to the other two freezing methods. PSF reduced the damage to myocytes and resulted in lower drip loss due to reduced microstructure disruption due to their small ice crystals, thereby maintaining the muscle tissue to better retain the fluids. Color and texture properties were less affected by PSF. Industrial relevanceFreezing is the most used preservation method for aquatic products. Rapid freezing results in better texture retention while the slow freezing damages the product texture because of the formation of extracellular large ice crystals developed during the freezing process. Thus, the nature of freezing affects the quality of frozen foods. Successful freezing processes aim at employing rapid freezing conditions which result in the formation of small ice crystals. Pressure shift freezing (PSF) is a novel technique with advantages of high degree of super-cooling, short phase transformation time, and results in very small ice crystals. This study makes use of a laboratory self-cooling system to carryout PSF of largemouth bass. This cooling system overcomes the limitation of previous studies on PSF which are expensive, limited to small size and impractical for commercial exploitations. The cooling system employed in this study can be easily adapted to large-scale production of PSF aquatic products. Test results provide a basis for the commercial exploitation of PSF for largemouth bass and such other aquatic foods for driving the quality advantage.

Cryoballoon ablation of left atrial roof with a novel cryoballoon system

Abstract Introduction A novel cryoballoon system (POLARx) has emerged and its efficacy regarding pulmonary vein isolation (PVI) has been already investigated. On the other hand, cryoballoon ablation of left atrial (LA) roof has been performed using a conventional cryoballoon system (Arctic Front Advance Pro [AFA-Pro]) in addition to PVI. However, cryoballoon ablation of LA roof with POLARx has not been investigated yet. Methods We performed cryoballoon ablation of LA roof with POLARx in 22 patients after we achieved PVI. After the cryoballoon ablation, complete conduction block at LA roof and isolation of all PVs were confirmed by creating an activation map during high right atrium pacing. If they could not be obtained with solely a cryoballoon, touch up ablation with radiofrequency ablation was permitted. The procedural data during ablation with POLARx was compared with those during ablation with AFA-Pro we had performed in a historical cohort of patients (n=46). Results Complete conduction block at LA roof without touch up ablation could be obtained in all the patients in POLARx group and 44 (95.7%) patients in AFA-Pro group. Total procedure time was almost similar in both groups (164.2±35.4 min for POLARx vs 180.3±35.4 min for AFA-Pro, p=0.10). During LA roof line ablation, nadir balloon temperature was significantly lower in POLARx group (right side: −53.6±4.4°C for POLARx vs −45.6±4.6°C for AFA-Pro, p&amp;lt;0.01, central part: −56.4±4.3°C for POLARx vs −46.0±3.7°C for AFA-Pro, p&amp;lt;0.01, left side: −55.1±3.5°C for POLARx vs −45.7±5.3°C for AFA-Pro, p&amp;lt;0.01), and balloon temperature reached −40°C earlier in POLARx (right side: 30.7±8.9 sec for POLARx vs 78.0±39.8 sec for AFA-Pro, p&amp;lt;0.01, central part: 30.6±9.3 sec for POLARx vs 65.9±33.3 sec for AFA-Pro, p&amp;lt;0.01, left side: 30.4±4.2 sec for POLARx vs 78.8±49.6 sec for AFA-Pro, p&amp;lt;0.01). Total freezing time required for LA roof line ablation was significantly shorter in POLARx group (589.3±163.6 sec for POLARx vs 877.5±191.7 sec for AFA-Pro, p&amp;lt;0.01).The scar area created after LA roof line ablation was similar in both groups (9.3±4.1 cm2 for POLARx vs 11.0±4.8 cm2 for AFA-Pro, p=0.23). Conclusion Complete conduction block at LA roof could be obtained after cryoballoon ablation with POLARx, in the same way as AFA-Pro. Lower nadir balloon temperature could be expected in shorter freezing time during LA roof line ablation in using POLARx compared with AFA-Pro. Funding Acknowledgement Type of funding sources: None.

Importance of Parameterizing Lake Surface and Internal Thermal Processes in WRF for Simulating Freeze Onset of an Alpine Deep Lake

AbstractThe alpine lakes widely distributed over the Tibetan Plateau (TP) are not only highly sensitive to climate but also regulate the regional climate. However, the lack of TP alpine lake observations limits the understanding of the lake‐atmosphere interactions. Here, we show the relative importance of parameterizing lake surface and internal thermal processes in describing the lake energy budget and lake‐atmosphere interactions. Based on the in situ observations at Lake Nam Co, a large and deep lake in the TP, we employed the coupled Weather Research and Forecasting with lake (WRF‐Lake) model to clarify their relative roles. Results show that the original model produces cold biases and too early timing of lake freeze onset. The adjustments of parameterizations of lake internal (temperature of maximum water density, extinction coefficient) and lake surface (roughness length) processes significantly improve the ability of the WRF‐Lake in simulating the lake thermal features and the freeze onset timing. The different parameterizations of lake internal thermal processes affect the onset timing of lake freeze mainly by altering the release of turbulent heat fluxes in summer, but the adjustments of lake surface roughness lengths change the turbulent heat fluxes during the unfrozen season from summer through early winter. Accordingly, the simulated lake freeze onset is much more sensitive to the surface roughness length schemes than to the internal thermal processes schemes. As the lake‐atmosphere interactions are very sensitive to the lake freeze onset, our results are critical for understanding and simulating the impact of TP lakes on the regional climate.

Aggregation properties and structure of chia seed gum and gluten protein mixtures after freezing storage

Chia seed gum (CSG) plays an important role in the aggregation and structural properties of gluten protein. The experimental results showed that adding 1.0 % CSG increased the freezing rate and shortened the freezing time by 42.3 % compared with gluten without CSG. At the same time, CSG had no significant effect on the composition of the gluten subunit but could better control the change in binding water and delay the structural deterioration caused by the extension of time (30 d). The viscoelasticity of gluten was increased, but only with the addition of 0.2–0.6 % CSG. In addition, it increased the denaturation transition temperature (Tp) and the degradation temperature (Td) of gluten protein to reduce the occurrence of recrystallization and resist pyrolysis. During frozen storage, gluten can form fine ice crystals and inhibit the transformation of α-helices and β-turns to random coils and β-sheets, which is more conducive to long-term frozen storage.

SVF-GEL Cryopreserved for Different Times Exhibits Varied Preservation and Regeneration Potential After Transplantation in a Mouse Model

BackgroundMatrix vascular component (SVF) gels derived from fat preserve tissue integrity and cell viability under cryopreserved conditions, making them easy to inject again for later use. Here, we compared the preservation power and regeneration potential of SVF-gel under different cryopreservation times.MethodsThe SVF-gel stored under − 20 °C, without cryoprotectant cryopreservation for 5, 15, and 45 days, with fresh SVF-gel as control. We evaluated the rate of volume retention after thawing the SVF-gel and the apoptosis rate of adipose-derived stem cells. Next, we analyzed retention rated, adipogenesis, angiogenesis, and connective tissue hyperplasia of the grafts, one month after subcutaneously transplanting the specimen into immunodeficient mice.ResultsSVF-gel cryopreserved for 5 and 15 days exhibited no significant different in apoptosis rates relative to the control group. Extending the cryopreservation time to 45 days resulted in significantly increased and decreased apoptosis and volume retention rates of SVF-gel, respectively. SVF-gel grafts cryopreserved for 5 and 15 days exhibited no significant differences from those in the control group, although their weights and volumes still fluctuated. Extending the cryopreservation time to 45 days resulted in significantly decreased retention rates of the grafts. Histologically, extending freezing time resulted in a gradual decline in the graft’s health adipose tissue, as well as decreased angiogenesis, and connective tissue hyperplasia.ConclusionSimple freezing of SVF-gel at − 20 °C conferred them with sufficient cell viability. Notably, short-term cryopreservation did not significantly increase the apoptosis rate, and it still had a certain regeneration after transplantation. However, prolonging freezing time to 45 days resulted in increased apoptosis rate and worsened transplantation effect.No Level AssignedThis journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Preparation and anti-icing performance of liquid lubricant micro-nano composite coating based on modified nano-SiO2

Lubricant coating is an efficient method for preventing ice formation on the surface of wind turbine blades. However, lubricants are frequently lost during the freezing and deicing cycles, along with the migration of frost or ice. As a result, developing a lubricating anti-icing coating with high wear resistance and stability is critical for resolving the icing problem on fan blades. In this paper, 3-Aminopropyltriethoxysilane (KH-550) coupling agent was used to modify the nano-SiO2 particles to construct the micro-nano rough surface of the coating. Then, liquid paraffin lubricant was injected to obtain a new type of self-supplemented lubricating micro-nano composite coating, and its mechanical wear resistance and anti-icing performance were explored. The experimental results show that the contact angle of the liquid lubricating liquid micro-nano composite coating is still >105° and the sliding angle is <15° after 50 wear tests, showing good ice repellency, indicating that its wear resistance is enhanced. According to the standard ISO 2049, the mechanical adhesion reaches grade 0, showing good mechanical stability. The ice adhesion of the composite coating is 85.6% lower than that of the unlubricated sample, and the mechanical interlock between ice and the rough surface was greatly reduced. In comparison to the non-lubricating liquid coating, the micro-nano composite coating effectively extends the total freezing time of water droplets, reaching 821 s and demonstrating good anti-icing performance.

Temperature Field and Stability Analysis of the Frozen Wall Based on the Actual Position of Freezing Holes

Taking the Qingdong Mine as the research object, combined with field measurement data, numerical simulation and theoretical analysis are used to examine the temperature field and stability of the frozen wall in the mine, respectively. The results show that during the active freezing period, under the same freezing time, the average temperature of the effective frozen wall of the fine sand layer is 0.2–1.0 and 0.5–2.5 °C lower than that of the sandy clay layer and clay layer, respectively. The effective frozen wall thickness of the fine sand layer is 0.04–0.17 and 0.17–0.33 m larger than that of the sandy clay layer and clay layer, respectively. The soil cooling between the two circles of freezing holes is the fastest. Due to the deflection of the freezing holes, the interface temperature field is asymmetrical. For deep clay with a depth of 200–250 m, it is most economical and reasonable for the brine temperature in the active freezing period to be −25 and −30 °C. At the designed brine temperature for cooling, during the excavation of the control layer of the topsoil layer (−216 m sandy clay), the side-wall temperature, average temperature, and thickness of the frozen wall meet the design requirements. The ultimate bearing capacity of the frozen wall is 3.20 MPa. When the well is empty for 30 h after excavation, the maximum radial displacement is 26.85 mm, so the frozen wall strength and stability are in a safe state. Overall, the findings of this study can serve as a useful reference for similar freezing projects.

Preparation, characterisation, and anti-icing properties of superhydrophobic coatings on asphalt mixture

ABSTRACT In order to reduce the safety risk caused by icing on asphalt pavement, we propose a new method to prepare a superhydrophobic coating (SHC) on asphalt mixture surfaces for anti-icing purposes. The nano-SiO2 particles modified by a coupling agent (KH550), and oxysilane were sprayed on the asphalt mixture surfaces to prepare the SHC. Fourier transform infra-red spectra prove that Si-O-Si and C–H are the main components of the superhydrophobic materials, and the coupling agent has a good cross-linking effect. SEM images reveal that SHCs have a micro nano-binary composite structure, and show excellent super-hydrophobicity. Moreover, when the spraying amount of the SHC with nano-SiO2 (30 nm), KH550 (4 ml), MTMS (6 ml) and DMDS (4 ml) on asphalt mixture was 40 ml, the contact angle presented the highest value of 154.2°. The anti-icing tests confirm that the SHCs can effectively delay the freezing time of surface water and decrease the adhesion force between the ice and the pavement. The simulated rainfall test verifies that the superhydrophobic properties of SHCs become worse after water washing. After 2 h of droplet impact, the contact angle of the SHC surface on asphalt mixture is still close to 150°, and SHCs still have good hydrophobic properties.

A new freezing model of sessile droplets considering ice fraction and ice distribution after recalescence

In this work, a new three-dimensional sessile droplet freezing model, involving the ice fraction and ice distribution after the droplet recalescence, is established based on the many-body dissipative particle dynamics with the energy conservation method for the first time. The proposed model is verified by comparing it with experimental results, and the accuracy of this model increases as the ice distribution becomes more non-uniform after recalescence. Furthermore, the effects of surface contact angle, droplet volume, surface temperature, and droplet supercooling degree on the freezing process are investigated in detail. The numerical results demonstrate that the angle of ice tips maintains a constant under various conditions. The upper and lower limits of solidification time under specific conditions are derived, and the droplet solidification time decreases linearly with the increase in supercooling. In addition, the average droplet solidification rate decreases with the increase in droplet volume, contact angle, and surface temperature, and the surface temperature is demonstrated to have the greatest influence on the solidification rate. Emphatically, we put forward an empirical formula, as a function of droplet volume, contact angle, droplet supercooling degree, and surface temperature, to predict the freezing time of a sessile supercooled droplet.

Fabrication of anti-icing/de-icing superhydrophobic composite coating based on hydrangea-like ZnO@CuS

Considering the destructive effect of ice accumulation on material surfaces, substantial attention has been devoted to fabricating anti-icing superhydrophobic coatings. However, most superhydrophobic coatings cannot deice. Herein, a special nanofiller was designed and fabricated as the main component of a superhydrophobic coating for simultaneously improving its anti-icing and de-icing performance. Firstly, hydrangea-like ZnO@CuS (H–ZnO@CuS) was synthesized via a precipitation process at room temperature. Then, a superhydrophobic composite coating composed of epoxy resin (ER), H–ZnO@CuS, and polydimethylsiloxane (PDMS) was fabricated on the Al surface via a layer-by-layer spraying process. The results demonstrate that, after 100 tape peeling tests and 40 abrasion cycles, the hydrophobicity of the ER/H–ZnO@CuS/PDMS composite coating remains basically unchanged, and its water contact angle (WCA) can still reach 156.3°, thus exhibiting excellent superhydrophobicity and mechanical durability. More importantly, the composite coating displays outstanding anti-icing and de-icing performance, which can prolong the static freezing time of water droplets from 3 to 13 min at −15 °C and prevent the formation of ice when water is dripped continuously for 20 min at −10 °C. Additionally, the melting time of ice at −15 °C can be shortened from 5 to 1 min due to the photothermal behavior of H–ZnO@CuS. Therefore, this work presents a promising strategy to endow coatings with simultaneous anti-icing and de-icing performance. This approach can not only improve the current efficiency of de-icing/anti-icing processes but also reduce the energy consumption by effectively reducing or eliminating the accumulation of water on the structure surface before it freezes. • A special hydrangea-like composite nano-fillers as the main component of superhydrophobic coating was fabricated. • The composite coating exhibited superhydrophobicity with water contact angle of 163.5 ± 1.9° and slide angle of 3.1 ± 0.2°. • Photothermal micro/nano structure endows coating with good anti-icing and de-icing performances simultaneously • The de-icing process of ice bead on the superhydrophobic coating at −15 °C completed within 1 min by photothermal effect. • This method provides new ideas for the preparation of anti-icing and de-icing coatings for practical outdoors applications.

EFFECT OF FREEZING PRESERVATION PERIOD ON SOME SENSORY CHARACTERISTICS OF THREE IRAQI LOCAL FISH SPECIES

The current study was conducted to determine the ideal period for freezing of three fish species of in the Iraqi local markets which are common carp Cyprinus carpio ,catfish Silurus triostegus and mullet Planiliza abu through sensory evaluation and the effect of freezing time on the flavor, juiciness and general acceptability of fish .A total of20 samples, were taken for each species of fresh local fish and were frozen at 18°C for different freezing periods : 1 day (T2), 15 days (T3), 30 days (T4) and 45 days (T5) , in addition to the fresh treatment T1 that has not been subjected to freezing. Results of common carp showed that the best freezing time was recorded for treatments T2, T3 and T4 which attained 6.8, 6.6 and 6.2, respectively, for the flavor. The treatment T2, T3 and T4 were recorded 6.4, 6.8 and 6.6 respectively, for tenderness .The treatments T2, T3 and T4 were amounted 7.4, 6.6 and 6.6 respectively, for the Juiciness. Results of the general acceptance of treatments T2, T3 and T4 were 7.6, 7.2, 6.6 respectively. Results of the catfish and the mullet for flavor showed that the best freezing period was for the two treatments T2 and T3, which were 7.4, 6.4 in the catfish and 6.6 and 5.4 in the mullet respectively. T2 and T3 continued to be significantly superior to the freshness of the catfish and the mullet over T4 and T5 and it was 7.0, 6.4 for the catfish and 5.8, 5.6 for the mullet, respectively. T2 and T3 were superior for the juiciness of catfish by 7.0 and 6.6 and for mullet, 5.8 and 5.6 respectively. As for the trait of general acceptance, it was superior in the two treatments T2 and T3 for catfish and mullet and they were 7.4, 6.8 for catfish 6.8 and 6.4 for mullet respectively.

Optimization of the Cooling Scheme of Artificial Ground Freezing Based on Finite Element Analysis: A Case Study

The present study was envisaged to evaluate the influence of different brine cooling schemes on the freezing process in the formation of sand-cobble strata in an underground connection aisle in Hohhot, China. The brine cooling schemes were set up by modifying the starting and ending brine temperatures in the construction of an underground connection aisle. Using ADINA finite element software, the simulation of the temperature field during the freezing process of the sand and pebble strata under three different schemes was performed. It was found that the freezing process was accelerated by lowering the freezing start temperature during the cooling process when the starting and ending brine temperatures remained unchanged. Furthermore, if the initial freezing temperature was changed, keeping the same freezing time at constant soil thermophysical parameters, the final effective thickness of the frozen wall was almost identical. Considering the same location of the temperature measurement points, the measured temperature of the inner and outer holes of the freezing curtain was found to be consistent with the numerical simulation, demonstrating the rationality of the numerical model. On the basis of this study, a brine cooling plan is proposed, which could serve as a reference for future construction.