Multiple Freeze Research Articles

Experimental Study on Water and Salt Migration and the Aggregate Insulating Effect in Coarse-Grained Saline Soil Subgrade under Freeze–Thaw Cycles

Understanding multiphase transformations and the migration of heat, water, vapor, and salt in coarse-grained saline soil under groundwater recharge and environmental freeze—thaw cycles is crucial for ensuring the stability of highway infrastructures. To clarify the water, heat, vapor, and salt migration patterns in coarse-grained saline soil, as well as the salt-insulating effect of the aggregate insulating layer, an experimental study was conducted in a soil column model under pressureless water replenishment with fluorescein-labeled liquid water under freeze—thaw cycles. The results showed that the temperature in the saline soil columns periodically changed and that hysteresis effects occurred during temperature transfer. External water replenishment and the content of liquid water inside the soil exhibited nonlinear changes with environmental temperatures. After multiple freeze—thaw cycles, two water and salt accumulation zones formed within the coarse-grained saline soil subgrade. The migration of liquid water resulted in a water and salt accumulation zone in the nonfrozen zone, whereas the migration of water vapor yielded a water and salt accumulation zone in the frozen zone. To prevent water and salt migration, a 20 cm thick gravel insulating layer could be laid at a distance of 10 cm from the bottom of the roadbed, which could provide a satisfactory salt-insulating effect. The research results provide a theoretical basis and guidance for regulating the stability of subgrades in saline soil areas.

Comparing energy and exergy of multiple effect freeze desalination to MEE MSF RO

Freeze desalination is a promising technique for wastewater treatment and zero/minimum liquid discharge systems, often requiring multiple stages to produce potable water. This research focuses on developing a Multiple Effect Freeze Desalination (MEFD) system based on experimental data for Single-Stage Desalination Efficiency (SSDE) and Single-Stage Recovery Rate (SSRR). The study analyzes various MEFD setups, calculating cooling energy consumption and correlating it with electrical usage through the coefficient of performance (COP). Comparisons with Reverse Osmosis (RO), Multi Effect Evaporation (MEE), and Multi-Stage Flashing (MSF) suggest that MEFDs may face challenges in matching RO efficiency but can compete with MEE and MSF within specific operational ranges. Exergy assessments indicate difficulties against even 10-stage MSF systems. Achieving SSDE and SSRR levels above 65% enables MEFDs to rival 10-stage MSF plants in terms of energy efficiency, surpassing MEE and MSF at over 85% efficiency. Despite these challenges, MEFDs offer benefits for treating high salt concentrations and resisting corrosion.

Mesoscopic damage mechanism of multiple freeze–thaw cycles of cement gravel based on particle flow theory

Mesoscopic damage mechanism of multiple freeze–thaw cycles of cement gravel based on particle flow theory

Biocompatibility Analysis of Mouse Spleen-Derived Extracellular Matrix

Background & Objectives: This study aimed to construct a decellularized mouse spleen scaffold and evaluate its cellular compatibility in vitro using murine bone marrow-derived mesenchymal stem cells (BM-MSCs). Materials & Methods: A combination of physical, chemical, and enzymatic treatments was employed for mouse spleen decellularization. These included multiple freeze- thaw cycles, the ionic detergent sodium dodecyl sulfate (SDS), and enzymatic trypsin. Histological and scanning electron microscopy analyses were conducted up to 7 days post-culture to assess the impact of decellularization and cellular adaptation to the spleen scaffolds. Results: Histological studies revealed the attachment and penetration of BM-MSCs into the scaffolds on days 5-7 following cell seeding. Furthermore, cell migration into the scaffold was observed 5 days after the seeding process. Conclusion: The decellularization approach utilized in this study proved to be effective and biocompatible, supporting the preservation and proliferation of BM-MSCs. These findings indicate its potential for spleen tissue engineering applications.

Design and Water Stability Evaluation of Cold Mix Emulsified Asphalt Mixture under Multiple Freeze–Thaw Cycles

Design and Water Stability Evaluation of Cold Mix Emulsified Asphalt Mixture under Multiple Freeze–Thaw Cycles

Simultaneous determination of choline, L-carnitine, betaine, trimethylamine, trimethylamine N-oxide, and creatinine in plasma, liver, and feces of hyperlipidemic rats by UHPLC-MS/MS

BackgroundDue to the close correlation between choline, L-carnitine, betaine and their intestinal microbial metabolites, including trimethylamine (TMA) and trimethylamine N-oxide (TMAO), and creatinine, there has been an increasing interest in the study of these compounds in vivo. MethodsIn this study, a rapid stable isotope dilution (SID)-UHPLC-MS/MS method was developed for the simultaneous determination of choline, L-carnitine, betaine, TMA, TMAO and creatinine in plasma, liver and feces of rats. The method was validated using quality control (QC) samples spiked at low, medium and high levels. Second, we applied the method to quantify the effects of Rosa Roxburghii Tratt juice (RRTJ) on plasma, liver, and fecal levels of choline, L-carnitine, betaine, TMA, TMAO, and creatinine in high-fat diet-induced hyperlipidemic rats, demonstrating the utility of the method. ResultsThe limits of detection (LOD) were 0.04–0.027 µM and the limits of quantification (LOQ) were 0.009–0.094 µM. The linear ranges for each metabolite in plasma were choline1.50–96 µM; L-carnitine: 2–128 µM; betaine: 3–192 µM; TMA: 0.01–40.96 µM; TMAO: 0.06–61.44 µM and creatinine: 1–64 µM (R2 ≥ 0.9954). The linear ranges for each metabolite in liver were Choline: 12–768 µM; L-carnitine: 1.5–96 µM; betaine: 10–640 µM; TMA: 0.5–32 µM; TMAO: 0.02–81.92 µM and creatinine: 0.2–204.8 µM (R2 ≥ 0.9938). The linear ranges for each metabolite in feces were choline: 1.5–96 µM; L-carnitine: 0.01–40.96 µM; Betaine: 1.5–96 µM; TMA: 1–64 µM; TMAO: 0.02–81.92 µM and Creatinine: 0.02–81.92 µM (R2 ≥ 0.998). The intra-day and inter-day coefficients of variation were < 8 % for all analytes. The samples were stabilized after multiple freeze–thaw cycles (3 freeze–thaw cycles), 24 h at room temperature, 24 h at 4 °C and 20 days at −80 °C. The samples were stable. The average recovery was 89 %-99 %. This method was used to quantify TMAO and its related metabolites and creatinine levels in hyperlipidemic rats. The results showed that high-fat diet led to the disorder of TMAO and its related metabolites and creatinine in rats, which was effectively improved after the intervention of Rosa Roxburghii Tratt juice（RRTJ）. ConclusionsA method for the determination of choline, L-carnitine, betaine, TMA, TMAO and creatinine in plasma, liver and feces samples was established, which is simple, time-saving, high precision, accuracy and recovery.

Repeated freezing to very low temperatures does not impact the amount ejected from EpiPen® and Jext® adrenaline autoinjectors

ABSTRACT It has previously been shown that EpiPen® autoinjectors are likely to activate normally following up to five excursions to −25°C but data about the post-freezing performance of other brands of adrenaline autoinjectors has not previously been published. Additionally, conditions experienced by polar medics may be substantially colder than this and the performance of adrenaline autoinjectors following more extreme freeze–thaw cycles remains uncharacterised. Investigators in Antarctica and the United Kingdom performed laboratory testing on two brands of adrenaline autoinjector, EpiPen® and Jext® (12 devices of each type). A single freeze–thaw cycle involved freezing the device to −80°C then allowing it to come to room temperature. Devices were exposed to 0, 1, 5 or 15 freeze–thaw cycles. The mass of liquid ejected from each device, when activated, was then measured. No significant differences in the mass of the liquid ejected was found between the test groups. Multiple freeze–thaw cycles to −80°C are unlikely to significantly impact the amount of adrenaline solution expelled from EpiPen® and EpiPen® autoinjectors. This preliminary finding encourages further work investigating the safety and effectiveness of adrenaline autoinjectors after exposure to very low temperatures. This information would be valuable for future polar medics planning and delivering medical provision in extreme environments.

Long-term impact of multiple freezes during cryoballoon pulmonary-vein isolation on atrial arrhythmia recurrence

Abstract Background Cryoballloon pulmonary vein isolation (CryoPVI) is well established for atrial fibrillation (AF) ablation. Nevertheless, it is still important to identify possible periprocedural factors influencing its efficacy. With difficult anatomical conditions it is currently unclear whether the number of cryoballoon applications needed to achieve complete vein isolation has an impact on the long-term effectiveness of CryoPVI. Methods We prospectively analyzed AF patients who underwent first-time CryoPVI in a single center cohort between 2018-2023. The group allocation depended on the number of cryo applications until complete isolation was achieved. CryoPVI was performed in a standardized procedure. Follow-up was performed after 3, 6, 12, 18, 24 and 36 months post CryoPVI. Efficacy endpoint was the occurrence of symptomatic atrial arrhythmia. Results A total of 1170 patients were included in the study. Of these, in 610 patients received only one cryoballoon application per pulmonary vein to achieve complete isolation. Gender distribution (56.7% male vs. 43.3% male p=0.09) and AF phenotype (38.5% persistent AF vs. 61.5% paroxysmal AF, p=0.23) did not differ significantly between the two groups, patients who received only cryoballoon application were older (70.1 vs. 68.5, p=0.006) and accordingly had higher CHADS-VASc (2.86 vs. 2.62, p=0.006). After 36 months no difference in the efficacy endpoint was observed between the two groups (47.6% vs. 43.2%, p=0.53). Complications included three major access complications (0.5% vs. 0.5%) and one stroke within the first 30 days after the procedure (0.2% vs. 0.2%) in each group. No pericardial tamponade occurred. Conclusion Multiple- freezes during CryoPVI have no influence on atrial arrhythmia recurrence.

Highly Mechanical Strength, Flexible and Stretchable Wood-Based Elastomers without Chemical Cross-Linking

Wood exhibits a limited elastic deformation capacity under external forces due to its small range of elastic limit, which restricts its widespread use as an elastic material. This study presents the development of a stretchable wood-based elastomer (SWE) that is highly mechanical and flexible, achieved without the use of chemical cross-linking. Balsa wood was utilized as a raw material, which was chemically pretreated to remove the majority of the lignin and create a more abundant pore structure, while exposing the active hydroxyl groups on the cellulose surface. The polyvinyl alcohol (PVA) solution was impregnated into delignified wood, resulting in the formation of a cross-linked structure through multiple freeze–thaw cycles. After eight cycles, the tensile strength in the longitudinal direction reached up to 25.68 MPa with a strain of ~463%. This excellent mechanical strength is superior to that of most wood-based elastomers reported to date. The SWE can also perform complex deformations such as winding and knotting, and SWE soaked in salt solution exhibits excellent sensing characteristics and can be used to detect human finger bending. Stretchable wood-based elastomers with high mechanical strength and toughness have potential future applications in biomedicine, flexible electronics, and other fields.

Physical and mechanical characteristics deterioration and crack evolution of sandy mudstone in an open-pit mine under multiple freeze–thaw cycles

In open-pit mines located in cold regions north of the 38°N latitude, there are significant freeze–thaw phenomena in slope rocks. This study conducted freeze–thaw cycle tests, considering the number of freeze–thaw cycles and the freezing temperature, on sandy mudstone commonly found in the slopes of open-pit mines. The investigation focused on the effects of freeze–thaw cycles on the physical and mechanical properties and acoustic emission (AE) characteristics of sandy mudstone. The results show that, with an increase in the number of freeze–thaw cycles and a decrease in freezing temperature, the sandy mudstone specimens exhibit nonlinear exponential changes in mass loss rate, P-wave velocity loss rate, peak strain, uniaxial compressive strength (UCS) and elastic modulus, and the amplitude of these changes gradually decreases. The stress–strain curves of specimens shift gradually from apparently brittle to plastic. Simultaneously, the microstructure changes from dense to loose, the micro surface transitions from flat to rough, and cracks and pore defects gradually develop. The peak AE ringing counts, cumulative AE ringing counts, crack initiation stress, and crack damage stress of the specimens all decrease with an increase in the number of freeze–thaw cycles and a decrease in freezing temperature. This suggests a shift from brittle failure to ductile failure. However, the ratio of crack initiation stress and crack damage stress to peak stress does not vary significantly with the number of freeze–thaw cycles and freezing temperature.

Strength and Durability Characterization of Structural Concrete Made of Recycled Plastic.

This study investigates the feasibility of utilizing recycled plastic waste as a partial substitute for sand in concrete production. Reprocessing used plastic items or materials involves collecting, cleaning, shredding, and melting, resulting in reprocessed plastic particles. Incorporating these recycled plastic particles into concrete addresses environmental concerns related to plastic disposal and the growing scarcity and increasing cost of natural sand. To evaluate the sand replacement capacity of recycled plastic, four types of mixtures were created with varying levels of recycled plastic replacement (5%, 10%, 15%, and 20%). All mixtures maintained a water-to-binding ratio of 0.55 and were tested at 7, 28, and 56 days. The testing regimen encompassed determining the slump value, density, compressive strength, tensile strength, and resistance to freezing and thawing. The findings revealed that replacing sand in the concrete mix with recycled plastic enhanced workability, which was attributed to the hydrophobic nature of the plastic particles. However, both compressive and tensile strength exhibited a declining trend. Additionally, after undergoing multiple freezing and thawing cycles, the concrete mix exhibited poor durability properties and brittleness. These issues may arise due to factors such as incompatibility, non-uniformity, reduced cohesion, and the lower density of plastic particles.

Abstract 6902: Development of a stable luciferase expressing PDX-derived cell line for translational in vitro and in vivo testing

Abstract Despite much effort invested in developing novel cancer therapies, more than 90% of clinical studies fail due to toxicity or lack of efficacy in patients. This can mainly be ascribed to lack of relevant and translational preclinical models. A common model used in preclinical studies is the xenograft model using immortalized cancer cells. Cell line-based models are cost efficient and can be genetically manipulated but are often criticized for lacking translational value. A murine model with higher clinical relevance is the patient derived xenografts (PDX) model established by implanting patients’ tumor tissue onto immunodeficient mice. Knowledge of patient therapy response, mutational status and tumor heterogeneity makes it a relevant model. However, PDX models are costly, not applicable for in vitro assays or subjective to genetic manipulation. To more closely mimic in vivo tumors we have established a PDX-derived cell line (PDXc) and characterized it extensively in a head-to-head comparison to the parental PDX model. Cells were isolated from a subcutaneous (SC) glioblastoma (GBM) PDX tumor (ST146), processed into single cells and cultivated in vitro. Once the PDXc were stable over several passages the cells were re-implanted into mice. Tumor take and growth rate were evaluated against the parental PDX model and common characteristics of the model such as EFGR and Vimentin expression were determined by IHC. We furthermore generated a stable Luciferase expressing PDXc using 3rd generation lentiviral particles and implanted the cells in an intracranial (IC) model of GBM. Tumor growth was evaluated using bioluminescence imaging (BLI) and MRI. Upon multiple passages and freeze cycles the cell line (ST146c) exhibited a stable in vitro doubling time (2.6 ± 0.2 days) with a morphology like other GBM cell lines with formation of neurospheres. STR analysis confirmed a genetic identical profile to ST146. ST146c implanted into mice had similar tumor take and growth rates to the parental PDX when injected IC (&amp;gt;90%, Td=3 d) and SC (&amp;gt;75%, Td=6 d). We also showed that ST146c had more homogeneous tumor growth. Ex vivo analysis showed similar expressions of EGFR (-), Vimentin (+++) and Ki67 (++) between the models. The BLI signal obtained from luciferase expressing ST146c implanted orthotopically was correlated to tumor volume obtained by MRI. We developed a PDX cell line that preserved critical in vitro and in vivo characteristics of the PDX model such as doubling time, tumor take rate and marker expression making it feasible to use the PDXc model in future preclinical studies. This will allow in vitro screens with patient derived tumor cells. Furthermore, the expression of luciferase in the PDXc enables intracranial and metastatic implantation with tumor monitoring using BLI. This platform consisting of in vitro and in vivo PDX models could be used as a predictive translational platform for testing new cancer therapies. Citation Format: Sigrid Cold, Rikke N. Bøge, Emma Papin, Ida T. Michler, Lotte K. Kristensen, Trine B. Engel, Andreas Kjaer, Carsten H. Nielsen, Sebastian Gnosa. Development of a stable luciferase expressing PDX-derived cell line for translational in vitro and in vivo testing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6902.

Effect of very long-term storage and multiple freeze and thaw cycles on 11-dehydro-thromboxane-B2 and 8-iso-prostaglandin F2α, levels in human urine samples by validated enzyme immunoassays

Biological samples are often frozen and stored for years and/or thawed multiple times, thus assessing their stability on long-term storage and repeated freeze–thaw cycles is crucial. The study aims were to assess:—the long-term stability of two major enzymatic and non-enzymatic metabolites of arachidonic acid, i.e. urinary 11-dehydro-thromboxane-(Tx) B2, 8-iso-prostaglandin (PG)F2α, and creatinine in frozen urine samples;—the effect of multiple freeze–thaw cycles. Seven-hundred and three urine samples measured in previously-published studies, stored at −40 °C, and measured for a second time for 11-dehydro-TxB2 (n = 677) and/or 8-iso-PGF2α (n = 114) and/or creatinine (n = 610) were stable over 10 years and the 2 measurements were highly correlated (all rho = 0.99, P < 0.0001). Urine samples underwent 10 sequential freeze–thaw cycles, with and without the antioxidant 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (10 mM); urinary 11-dehydro-TxB2 and creatinine were stable across all cycles (11-dehydro-TxB2: 100.4 ± 21%; creatinine: 101 ± 7% of baseline at cycle ten; n = 17), while 8-iso-PGF2α significantly increased by cycle 6 (151 ± 22% of baseline at cycle ten, n = 17, P < 0.05) together with hydrogen peroxide only in the absence of antioxidant. Arachidonic acid metabolites and creatinine appear stable in human urines stored at −40 °C over 10 years. Multiple freeze–thaw cycles increase urinary 8-iso-PGF2α in urine samples without antioxidants. These data are relevant for studies using urine samples stored over long-term and/or undergoing multiple freezing–thawing.

The deformation and failure characteristics of tunnels in layered rock with gentle dip angles after freeze–thaw cycles: Physical model tests and numerical investigation

When a tunnel passes through layered rock with a gentle dip angle in cold regions, the occurrence of multiple freeze–thaw (F–T) cycles can easily cause fatigue damage to the rock bedding surfaces and seriously affect the rock stability. One of the engineering problems that needs to be solved is to determine the deformation and failure mechanisms of such surrounding rock under F–T cycles. Based on the similarity principle, the mechanical response of the tunnel lining structure and the progressive failure process of the surrounding rock under long-term F–T action were studied by performing physical model tests and numerical simulations. The results show that the model tunnel lining partially separates from the surrounding layered rock with a gentle dip angle under the action of F–T cycles. Moreover, the load bearing capacity of the model weakens after undergoing F–T cycles. Additionally, the bending moment and axial force evolution characteristics of the tunnel and surrounding rock model are consistent with the deformation characteristics, which agree with the actual mechanical and deformation characteristics of a real tunnel under F–T cycles. After establishing numerical calculation models for surrounding rock with three bedding angles (0°, 10°, and 20°) and verifying the numerical models based on the test results, the horizontal and vertical displacements of the surrounding rock in the tunnel entrance section under ground stress conditions at a depth of 400 m were calculated. The research results accurately reflect the long-term deformation characteristics of layered rock with gentle dip angles surrounding tunnels in cold regions and can provide theoretical guidance for the application of corresponding tunnel support measures in cold regions.

Effect of Cryoprotectants on Quality of Desalted Jellyfish Subjected to Multiple Freeze- Thaw Cycles

A freeze-thaw cycle in frozen products occurs when the temperature fluctuates during storage or transportation, causing drip loss, changes in ice crystal reformation, and textural protein. In practical freezing, using cryoprotectants in frozen products aids in delaying the physicochemical changes. The problem has been found in commercial frozen jellyfish with sesame oil, causing the separating oil and water derived from drip loss of thawed jellyfish protein. This study aimed to select an appropriate cryoprotectant and concentration for frozen jellyfish products. Therefore, this research compared the changes in the physical and textural properties of desalted jellyfish collagen protein soaked in inulin, sucrose, or sorbitol at 1, 5, and 10% and subjected to three freeze-thaw cycles. Results showed increased concentration of each cryoprotectant increased soaking yield. The maximum soaking yields of desalted jellyfish were 2.49 ± 0.54, 2.79 ± 0.82, and 2.78 ± 0.51%, and each cryoprotectant content was 7.18 ± 0.01, 7.54 ± 0.00, and 8.58 ± 0.32% when using static soaked in inulin, sucrose, and sorbitol at 10%. During the freeze-thaw cycle, the retardation of the denatured jellyfish protein from ice crystals increased when desalted jellyfish were immersed in inulin, sucrose, or sorbitol at the maximum concentration of 10%, displaying the drip losses at 27.88 ± 0.45, 29.45 ± 0.35, and 28.56 ± 0.73% that lowered than the control at 56.54 ± 0.64%. The increased repeated freeze-thaw cycles increased the compact structure of thawed jellyfish collagen, supported by microstructure analysis. In summary, inulin at 10% appears to have a cryoprotective effect similar to sucrose and sorbitol and will be a choice for commercial frozen jellyfish-based food menu development.

Nearshore ice complex breakup is controlled by a balance between thermal and mechanical processes

AbstractShore ice is an important facet of cold‐climate coastal geomorphology yet is generally understudied in comparison to other aspects such as nearshore hydrodynamics. Climate change is resulting in more dynamic shore ice regimes (i.e., shortened ice season and multiple freeze–thaw cycles); thus, a clear understanding of the role of shore ice in coastal geomorphic evolution is needed. The presence of shore ice is generally thought to provide the coast a protective buffer from storm waves though some studies have indicated enhanced nearshore erosion and sediment transport associated with ice development. This is particularly apparent during the breakup phase of shore ice as sediment can be scoured from the bed, deposited in place, or transported offshore. Given this, understanding the mechanics of shore ice breakup is critical. This study documents the first combined field and laboratory evaluation of the physical conditions leading to shore ice breakup, detailing the complex interplay between thermal and mechanical processes in ice deterioration. Through a wave tank experiment as well as field observations, wave impacts alone are shown to be unlikely to cause breakup of shore ice and thermal weakening is required. This has important implications both for predicting when ice will break up as well as for identifying potential nearshore sediment transport pathways. If ice breaks up entirely from thermal degradation, then sediment is likely to be deposited in place, whereas if ice breaks up from a combination of thermal degradation and wave impact, then sediment can be redistributed across the shoreface. Monitoring of meteorological conditions during ice breakup can likely be used as a first‐order predictor of geomorphic changes resulting from shore ice deterioration.

Development of a Plasmodium vivax biobank for functional ex vivo assays

BackgroundPlasmodium vivax is the second most prevalent cause of malaria yet remains challenging to study due to the lack of a continuous in vitro culture system, highlighting the need to establish a biobank of clinical isolates with multiple freezes per sample for use in functional assays. Different methods for cryopreserving parasite isolates were compared and subsequently the most promising one was validated. Enrichment of early- and late-stage parasites and parasite maturation were quantified to facilitate assay planning.MethodsIn order to compare cryopreservation protocols, nine clinical P. vivax isolates were frozen with four glycerolyte-based mixtures. Parasite recovery post thaw, post KCl-Percoll enrichment and in short-term in vitro culture was measured via slide microscopy. Enrichment of late-stage parasites by magnetic activated cell sorting (MACS) was measured. Short and long-term storage of parasites at either − 80 °C or liquid nitrogen were also compared.ResultsOf the four cryopreservation mixtures, one mixture (glycerolyte:serum:RBC at a 2.5:1.5:1 ratio) resulted in improved parasite recovery and statistically significant (P < 0.05) enhancement in parasite survival in short-term in vitro culture. A parasite biobank was subsequently generated using this protocol resulting in a collection of 106 clinical isolates, each with 8 vials. The quality of the biobank was validated by measuring several factors from 47 thaws: the average reduction in parasitaemia post-thaw (25.3%); the average fold enrichment post KCl-Percoll (6.65-fold); and the average percent recovery of parasites (22.0%, measured from 30 isolates). During short-term in vitro culture, robust maturation of ring stage parasites to later stages (> 20% trophozoites, schizonts and gametocytes) was observed in 60.0% of isolates by 48 h. Enrichment of mature parasite stages via MACS showed good reproducibility, with an average of 30.0% post-MACS parasitaemia and an average of 5.30 × 105 parasites/vial. Finally, the effect of storage temperature was tested, and no large impacts from short-term (7 days) or long-term (7–10 years) storage at − 80 °C on parasite recovery, enrichment or viability was observed.ConclusionsHere, an optimized freezing method for P. vivax clinical isolates is demonstrated as a template for the generation and validation of a parasite biobank for use in functional assays.

Photothermal materials with energy-storage properties provide an energy-saving design for highly efficient anti-icing/deicing applications

All-weather, high-efficiency solar photothermal anti-icing/deicing systems are of great importance for solving the problem of ice accumulation on outdoor equipment surfaces. In this study, a photothermal phase change material with a micro-porous structure (MP@PPCM) is prepared via salt-template and melt-blending methods. Owing to the synergistic effect of the latent heat released from the phase change material and the thermal-insulation effect of the internal micro-porous structure, MP@PPCM exhibits a low cooling rate and a high equilibrium temperature during the cooling process. In addition, MP@PPCM exhibits excellent photothermal conversion performance under light illumination, providing the basis for highly efficient anti-icing/deicing. Notably, the single droplet icing and melting results show that the droplet has the longest icing delay time and the shortest melting time on the MP@PPCM sample compared to that on the other samples analyzed. Furthermore, day–night alternation, multiple freezing–melting, and chemical stability tests verify the outdoor applications potential of MP@PPCM. The study results provide a way to prepare high-efficiency photothermal anti-icing/deicing materials in the absence of light conditions.

O-051 Refreezing and rebiopsy – are these worth it?

Abstract Preimplantation genetic testing of embryos offers the opportunity to avoid the transmission of hereditary disorders to the offspring by selecting out embryos affected by a single gene mutation or mutations (PGT-M), structural rearrangements of chromosomes (PGT-SR), aneuploidy (PGT-A) as well as polygenic risk (PGT-P). Over the last two decades, laboratory techniques have seen tremendous developments including extended embryo culture to blastocyst stage, trophectoderm biopsy and vitrification. The latter technique is highly efficient and allows multiple freezing and warming cycles when performed in proficient laboratories. At the same time whole genome analysis techniques provide the opportunity to analyse embryonic DNA in great detail for multiple indications simultaneously. The PGT process is sensitive to both biological and technical issues which sometimes lead to a failed PGT result. Failure of PGT diagnosis is reported to occur in between 2-12% of PGT cycles depending on the methodology used. The main causes of inconclusive diagnosis are DNA amplification failure and non-concurrent results. Independent variables that influence inconclusive results are day of embryo biopsy, number of cells taken at biopsy and the quality of the IVF laboratory. In order to seize every opportunity in reaching a diagnosis and optimize reproductive outcome for the patient, rebiopsy and retesting (double biopsy and double cryopreservation) can be performed. In situations where embryos need to be biopsied for PGT for reasons of newly found genetic indications or the clinical need for PGT-A, and after an initial cryopreservation, single biopsy and double cryopreservation may be performed with potential effect on subsequent reproductive outcome. A limited number of studies have addressed both the feasibility as well as the success rate of rebiopsy and refreezing. Most studies conclude that the technique is efficient in terms of diagnostic efficiency and reproductive outcome, when performed in expert laboratories. A few studies have addressed the health of the children after multiple biopsy and multiple freezing and have not shown increased risks. Larger studies are needed to establish the true clinical and health-economic value of rebiopsy and refreezing. The speaker will give an overview of existing evidence in literature and assess whether it is safe and worthwile to go the extra mile and consider refreezing and rebiopsy for PGT. Trial registration number XXXX

Detection of specific RNA targets by multimerization

Detection of specific RNA targets via amplification-mediated techniques is widely used in fundamental studies and medicine due to an essential role of RNA in realization of genetic information and diseases development. Here, we report on an approach for detection of RNA targets based on a particular type of isothermal amplification, namely, reaction of nucleic acid multimerization. The proposed technique requires only a single DNA polymerase possessing reverse transcriptase, DNA-dependent DNA polymerase and strand-displacement activities. Reaction conditions that lead to efficient detection of the target RNAs through multimerization mechanism were determined. The approach was approved using genetic material of SARS-CoV-2 coronavirus as a model viral RNA. Reaction of multimerization allowed to differentiate SARS-CoV-2 RNA-positive samples from SARS-CoV-2 negative samples with high reliability. The proposed technique determines detection of RNA even in samples, which undergone multiple freezing.