Freeze-thaw Cycles Research Articles

Impact of Preanalytical Procedures on Complement Biomarkers in Cerebrospinal Fluid and Plasma from Controls and Alzheimer's Disease Patients.

Studies comparing cerebrospinal fluid (CSF) and plasma complement proteins in Alzheimer's disease (AD) patients versus healthy controls (HC) have yielded inconsistent results. Discrepancies in the preanalytical sample handling could contribute to the heterogeneity in the reported findings. Using qualified immunoassays, we aimed at assessing the impact of preanalytical procedures on complement proteins in blood and CSF from AD patients and HCs. We supplemented HC and AD CSF/plasma with complement stabilizers and measured the complement proteins C4a, C4, C3a, C3, Factor Bb and Factor B by immunoassay. We tested the impact of freeze-thaw (FT) cycles on fluid complement proteins. Most complement proteins were mildly impacted by FT cycles in plasma but not CSF, except for C3a which displayed greater sensitivity to FTs in CSF than in plasma. In CSF, the effect of FTs on C3a was reduced but not prevented by the supplementation with EDTA (±Futhan). Our findings provide recommendations for CSF/plasma sample handling to ensure robust and reproducible complement biomarker analyses in AD.

Experimental investigation on the residual strength of concrete under the multi-factor coupling action of chloride penetration, freeze-thaw, and fatigue effect

With the ongoing process of globalization and the rapid expansion of the global economy, the proliferation of coastal constructions and infrastructures has witnessed a notable surge. These structures often encounter a confluence of environmental stressors in practical engineering, including cyclic fatigue loading, chloride salt erosion, and freeze-thaw cycles. These synergistic factors accelerate concrete’s failure, resulting in accelerated deterioration and significantly reduced durability. A comprehensive understanding of the damage characteristics of concrete materials in offshore environments, under the multi-factor coupled action of freeze-thaw phenomena, along with an assessment of their residual strength, is crucial for the development of relevant structural analysis and lifetime prediction models. To address this, twenty-seven dedicated specimens were designed and fabricated for this investigation. They were employed to scrutinize the residual strength of concrete under the combined influences of fatigue, freeze-thaw, and chloride penetration. Nine distinct multi-factor coupling actions were meticulously devised and characterized by different parameters. Following the multi-factor coupling action, tests were conducted to assess the residual flexural and compressive strengths, as well as the chloride ion content near the specimen edges. The findings revealed a substantial negative correlation between the residual flexural and compressive strengths with both the number of freeze-thaw cycles and fatigue loading iterations. In contrast, chloride ion concentration and the stress level of fatigue loading (stress ratio: 0.1–0.3) exhibited a comparatively marginal influence. Despite the relatively short test duration, it was evident that both freeze-thaw cycles and fatigue loading exerted a discernible promotional effect on chloride ion ingress in the concrete of the specimens.

Investigating the Role of Microclimate and Microorganisms in the Deterioration of Stone Heritage: The Case of Rupestrian Church from Jac, Romania

Natural stone can undergo disaggregation from various causes, including physical actions such as freeze–thaw cycles, temperature and humidity variations, chemical actions such as the solubilization of minerals by organic and inorganic acids, as well as biological actions due to the colonization of organisms that can produce biocorrosion and biomineralization. This research investigates the impact of microclimatic conditions and microbial activity on the physical and chemical integrity of stone heritage, particularly the biodeterioration caused by fungi in the case of a Romanian rock church. Various analytical techniques were employed, including macroscopic and optical microscopy, Raman spectroscopy, X-ray diffraction, and culture-based identification methods, to characterize the mineral composition and microbial contamination of the rock samples. The analyses revealed that the sandstone consists primarily of quartz (over 90%), muscovite (5–10%), and feldspars. The identified fungi included Cladosporium herbarium, Aspergillus niger, and Mortierella hyalina. The SEM images showed fungal hyphae and spores within the kaolinite–illite matrix, indicating significant microbial colonization and its role in rock deterioration. Additionally, microclimatic data collected over a 12-week period highlighted the substantial fluctuations in temperature and relative humidity within the church, which contribute to the physical and chemical weathering of the stone. This study also noted high levels of particulate matter (PM2.5 and PM10) and volatile organic compounds, which can exacerbate microbial growth and stone decay. The comprehensive analysis underscores the need for targeted preservation strategies that consider both microclimatic factors and microbial colonization to effectively conserve stone heritage sites, ensuring their longevity and structural integrity.

Self-powered strain sensing devices with wireless transmission: DIW-printed conductive hydrogel electrodes featuring stretchable and self-healing properties

With rapid advancements in health and human–computer interaction, wearable electronic skins (e-skins) designed for application on the human body provide a platform for real-time detection of physiological signals. Wearable strain sensors, integral functional units within e-skins, can be integrated with Internet of Things (IoT) technology to broaden the applications for human body monitoring. A significant challenge lies in the reliance of most existing wearable strain sensors on rigid external power supplies, limiting their practical flexibility. In this study, we present an innovative strategy to fabricate glutaraldehyde (GA)-poly(vinyl alcohol) (PVA)/cellulose nanocrystals (CNC)/Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) conductive hydrogels through multiple hydrogen bonding systems. Combining the advantageous rheological properties of the precursor solution and the high specific surface area after freeze–thaw cycling, we have created a self-powered sensing system prepared by large-area printing using direct ink writing (DIW) printing. The resulting conductive hydrogel exhibits commendable mechanical properties (411 KPa), impressive stretchability (580 %), and robust self-healing capabilities (>98.3 %). The strain sensor, derived from the conductive hydrogel, demonstrates a gauge factor (GF) of 2.5 within a stretching range of 0–580 %. Additionally, the resultant supercapacitor displays a peak energy density of 0.131 mWh/cm3 at a power density of 3.6 mW/cm3. Benefiting from its elevated strain response and remarkable power density features, this self-powered strain sensing system enables the real-time monitoring of human joint motion. The incorporation of a 5G transmission module enhances its capabilities for remote data monitoring, thereby contributing to the progress of wireless tracking technologies for self-powered electronic skin.

Study on performance deterioration and life prediction of reed straw-recycled brick aggregate concrete after freeze-thaw cycle

The current rate of carbon dioxide emissions poses a significant threat to global climate, making it increasingly important and urgent to lead the carbon-intensive construction industry to achieve carbon neutrality. Currently, the most practical method involves reusing waste materials. In this study, waste red bricks were used to replace 75 % of natural aggregates in concrete, and three different forms of reed stalks (including reed straw ash, reed straw strips, and reed straw powder) were added to prepare the recycled reed straw brick aggregate concrete (RSAC). Freeze-thaw tests were carried out for 25, 50, 75, and 100 cycles in water and sodium sulfate solution to establish a freeze-thaw deterioration model and perform life prediction. The results showed that the degree of freeze-thaw deterioration of the specimens in sulfuric acid solution was small, and the degree of deterioration of reed powder concrete (RSAC-F) and reed ash concrete (RSAC-H) was more serious than reed strip concrete (RSAC-T) and additive-free concrete (RSAC-0). After 100 water freeze-thaw cycles, the strength losses of the specimens were 21.55 %, 21.7 %, 18.71 %, and 20.54 %, and the relative dynamic elastic modulus losses were 6.11 %, 7.25 %, 4.39 %, and 5.79 %, and the mass losses were 1.79 %, 2.04 %, 1.4 %, and 1.5 %. The fitting results showed that the predicted values of the parabolic model and two-parameter Weibull distribution damage model were closer to the experimental values, and the fitting rates are both greater than 90 %. The life prediction results show that the freeze-thaw resistance of the four types of reed-brick aggregate recycled concrete can reach more than 80 years in southern China, meeting the durability requirements, and the RSAC-T and RSAC-0 group concrete could also be used in projects with lower frost resistance requirements in the north region of China.

Research on performance variations of different asphalt binders results from microwave heating during freeze-thaw cycles

Microwave heating (MH) as a sustainable pavement maintenance method can effectively repair the cracks caused by freeze-thaw (FT) damage. However, binders' properties may be weakened during this process then reduces the pavement life. For this purpose, this work aims to investigate the performance changes of neat binders (Nb) and high-viscous binders (Hb) during FT and MH. The physicochemical, rheological, and deformation properties are investigated after FT and MH. Results indicate that asphalt binders become harder and lead to an increase in carbonyl index (CI) and sulfoxide index (SI) after FT. MH has a limited damage level for binders especially for Hb, causing a slight increase in CI and SI, compared to binders after FT. Polymers play an important role in the viscoelastic responses of asphalt binders. Changes in viscoelastic properties of Nb mainly result from the binder damage of FT and MH, while viscoelastic changes of Hb are mainly due to the damage of polymers. This different damage mechanism causes Hb to show better resistance compared to Nb, which is reflected in modulus and phase angle. BBR tests indicate that MH can further deteriorate the damage of both binders, but Hb shows a lower performance decline compared to Nb, and it is recommended to conduct MH at the region with a minimum temperature above −12 °C. MSCR results reveal that FT and MH can improve the rutting resistance of Nb due to the hardening phenomenon after damage, and reduce the elastic stability of Hb due to the damage to polymers. In summary, Nb is sensitive to MH, its performance can be further damaged after MH. Hb has better resistance to MH, its properties do not further deteriorate, so Hb is more applicable to MH.

Screening and characterization of an antifreeze peptide from sea cucumber intestinal protein hydrolysates

Protein deterioration caused by ice crystals is an important factors affecting the frozen storage of fish. In this study, antifreeze peptides extracted from hydrolysates of sea cucumber intestinal protein with inhibition of protein denaturation were screened and characterized. The peptide Leu-Pro-Glu-Phe-Thr-Glu-Glu-Glu-Lys (LPEFTEEEK), derived from neutral protease hydrolysates of sea cucumber intestinal protein, was investigated for its potential to enhance the quality of salmon fillets during three freeze-thaw cycles. The results showed that the application of LPEFTEEEK effectively maintained the texture of fish fillets, as well as the oxidative and conformation stability of myofibrillar protein during the freezing process. Additionally, molecular dynamics simulations verified that LPEFTEEEK could bind to ice crystals and inhibit their recrystallization, thus preventing organisms from being damaged by freezing. This suggests that LPEFTEEEK holds significant promise as a novel cryoprotective agent for marine-derived antifreeze peptides.

A selective, sensitive and fast LC-MS/MS method for cabotegravir quantification in rat plasma and pharmacokinetic investigations.

This study presents a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying cabotegravir (CAB) in rat plasma. A novel, sensitive, and rapid LC-MS/MS method has been developed and validated. Furthermore, protein precipitation technique allowed us to lowered the limit of quantification (LOQ) to nanogram levels, allowing detection of smaller CAB amounts in plasma samples. A review of scientific literature reveals that this method is superior than published methods in terms of runtime, sensitivity, wide linearity, and cost, using LC-MS/MS to quantify CAB in biological samples. CAB reached its maximum concentration (Cmax) of 78.401 μg/mL in rat plasma at 1.50 h (Tmax). Linearity was evaluated across 0.05-1000 μg/mL for CAB using five calibration curves with at least nine standards each with r2 > 0.9997. The intra- and inter-day precision and accuracy results were below 15% and acceptable as per Food and Drug Administration (FDA) guidelines. Stability of compounds were established in a battery of stability studies, that is, benchtop, autosampler, and long-term storage stability as well as freeze thaw cycles. The validated method can be used as a routine method to support pharmacokinetic studies.

Conformations of membrane human immunodeficiency virus (HIV-1) envelope glycoproteins solubilized in Amphipol A18 lipid-nanodiscs.

Upon binding to the host cell receptor, CD4, the pretriggered (State-1) conformation of the human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) trimer undergoes transitions to downstream conformations important for virus entry. State 1 is targeted by most broadly neutralizing antibodies (bNAbs), whereas downstream conformations elicit immunodominant, poorly neutralizing antibody (pNAb) responses. Extraction of Env from the membranes of viruses or Env-expressing cells disrupts the metastable State-1 Env conformation, even when detergent-free approaches like styrene-maleic acid lipid nanoparticles (SMALPs) are used. Here, we combine three strategies to solubilize and purify mature membrane Envs that are antigenically native (i.e., recognized by bNAbs and not pNAbs): (1) solubilization of Env with a novel amphipathic copolymer, Amphipol A18; (2) use of stabilized pretriggered Env mutants; and (3) addition of the State-1-stabilizing entry inhibitor, BMS-806. Amphipol A18 was superior to the other amphipathic copolymers tested (SMA and AASTY 11-50) for preserving a native Env conformation. A native antigenic profile of A18 Env-lipid-nanodiscs was maintained for at least 7 days at 4°C and 2 days at 37°C in the presence of BMS-806 and was also maintained for at least 1 h at 37°C in a variety of adjuvants. The damaging effects of a single cycle of freeze-thawing on the antigenic profile of the A18 Env-lipid-nanodiscs could be prevented by the addition of 10% sucrose or 10% glycerol. These results underscore the importance of the membrane environment to the maintenance of a pretriggered (State-1) Env conformation and provide strategies for the preparation of lipid-nanodiscs containing native membrane Envs.IMPORTANCEThe human immunodeficiency virus (HIV-1) envelope glycoproteins (Envs) mediate virus entry into the host cell and are targeted by neutralizing antibodies elicited by natural infection or vaccines. Detailed studies of membrane proteins like Env rely on purification procedures that maintain their natural conformation. In this study, we show that an amphipathic copolymer A18 can directly extract HIV-1 Env from a membrane without the use of detergents. A18 promotes the formation of nanodiscs that contain Env and membrane lipids. Env in A18-lipid nanodiscs largely preserves features recognized by broadly neutralizing antibodies (bNAbs) and conceals features potentially recognized by poorly neutralizing antibodies (pNAbs). Our results underscore the importance of the membrane environment to the native conformation of HIV-1 Env. Purification methods that bypass the need for detergents could be useful for future studies of HIV-1 Env structure, interaction with receptors and antibodies, and immunogenicity.

Design of self-healing nanocomposite hydrogels and the application to the detection of human exercise and ascorbic acid in sweat

Hydrogel sensors have broad application prospects in human motion monitoring and sweat composition detection. However, hydrogel-based sensors are faced with challenges such as low accuracy and poor mechanical properties of analytes detection. Based on mussel-inspired chemistry, we synthesized mesoporous silica@polydopamine-Au (MPS@PDA-Au) nanomaterials and designed a self-healing nanocomposite hydrogel to monitor human movement and ascorbic acid detection in sweat. Mesoporous silica (MPS) possess orderly mesoporous structure. Dopamine (DA) polymerized on the surface of MPS to generate polydopamine (PDA), forming the composite material MPS@PDA-Au. This composite was then embedded into polyvinyl alcohol (PVA) hydrogels through a simple freeze-thaw cycle process. The hydrogels have achieved excellent deformable ability (508.6%), self-healing property (90.5%) and mechanical strength (2.9 MPa). The PVA/MPS@PDA-Au hydrogel sensors had the characteristics of fast response time (123.2 ms), wide strain sensing range (0–500%), excellent fatigue resistance and stability in human detection. The detection range of ascorbic acid (AA) in sweat was wide (8.0 μmol/L-100.0 μmol/L) and the detection limit was low (3.3 μmol/L). Therefore, these hydrogel sensors have outstanding application prospects in human motion monitoring and sweat composition detection.

Effect of freeze-thaw treatments with different conditions on frost fatigue in three diffuse-porous trees.

In addition to inducing xylem embolism, freeze-thaw events can cause frost fatigue phenomena. Freezing temperature, freezing times, number of freeze-thaw cycles and frost drought can affect the level of freeze-thaw-induced embolism, but it is unknown whether there is an effect on frost fatigue. We assessed whether these frost-related factors changed frost fatigue in the three diffuse-porous species by simulating freeze-thaw treatments under different conditions. We also proposed a new metric, embolism area, in place of embolism resistance, to more accurately quantify the shift of the vulnerability curve after experiencing freeze-thaw-induced embolism and refilling. Frost fatigue caused vulnerability curves of all species to change from S-shaped to double S-shaped or even R-shaped curves. When exposed to a freeze-thaw event, Acer truncatum showed strong resistance to frost fatigue; in contrast, Populus (I-101×84K) and Liriodendron chinense were more vulnerable. Changing freezing temperature and times did not impact the response to frost fatigue in the three species, but a greater number of freeze-thaw cycles and more severe frost drought significantly exacerbated their fatigue degree. Considering that frost fatigue may be a widespread phenomenon among temperate diffuse-porous species, more work is needed in the future to reveal the mechanisms of frost fatigue.

Plasma metabolic profiling reveals that crude and processed Polygonatum cyrtonema hua extract ameliorates myocardial ischemia-induced damage by regulating branched-chain amino acid and energy metabolism

Polygonatum cyrtonema Hua and its processed products have demonstrated cardio-protective effects, though the underlying mechanisms remain unclear. In this study, plasma metabolic profiling and pattern recognition were employed to explore the cardio-protective mechanisms of both crude and processed P. cyrtonema in a myocardial ischemia model induced by ligation, using gas chromatography-mass spectrometry. Post-modeling, plasma levels of creatine kinase-MB, lactate dehydrogenase, troponin T, and malondialdehyde were significantly elevated but were notably reduced after treatment. Conversely, plasma levels of glutathione peroxidase and superoxide dismutase, which were significantly decreased post-modeling, were restored following treatment. Hematoxylin-eosin (HE) and Masson staining revealed that both crude and processed P. cyrtonema effectively reduced inflammatory infiltration and fibrosis in cardiac tissue. Metabolic profiling identified 34 differential endogenous metabolites in the treatment groups, with 19 confirmed using standard compounds. The linear correlation coefficients (R2) for these standards ranged from 0.9960 to 0.9996, indicating high accuracy. The method exhibited excellent precision and repeatability, with relative standard deviation (RSD) values below 8.57%. Recovery rates were between 95.02% and 105.15%, and the stability of the standard compounds was confirmed after three freeze–thaw cycles, with RSD values under 4.42%. Both crude and processed P. cyrtonema were found to alleviate myocardial ischemia symptoms by regulating branched-chain amino acid metabolism and energy metabolism. These findings provide a solid foundation for the potential clinical use of this herb and its processed products in treating heart disease.

Frost resistance of recycled aggregate concrete subjected to coupling sustained compressive load and freeze-thaw cycles

Recycled aggregate concrete (RAC) structures situated in cold regions are required to withstand the combined effects of mechanical load and environmental factors throughout their operational lifespan. The influence of sustained load introduces complexity to the degradation mechanism of RAC. This research examines the frost resistance of RAC across varying levels of recycled coarse aggregate (RCA) replacement (0, 50 %, 100 %) and sustained compressive loading (0, 0.3 fc, 0.5 fc). The frost resistance was quantified by the indices of macroscopic morphology change, mass loss, relative dynamic modulus of elasticity, and mechanical properties. Results show that 0.3 fc can effectively improve the frost resistance of RAC, a trend that becomes more pronounced with increasing replacement rates of RCA. Excessive stress (0.5 fc) was found to be unfavorable to the frost resistance of RAC and increase the compressive strength variability of RAC after freeze-thaw cycles. Analysis of meso/micro-structure characteristics using optical and scanning electron microscopes, along with the mercury intrusion porosimetry, reveals that optimal compressive loading (0.3 fc) enhances mortar integrity, reduces porosity, and improves compactness, thereby bolstering RAC’s frost resistance.

Study on the Dispersion Characteristics of Coal Complex Resistivity under the Effect of Liquid Nitrogen Cyclic Freeze-Thaw and Evaluation of Permeability Enhancement.

The effect of liquid nitrogen freeze-thaw fracturing on coal seams can be potentially evaluated by the complex resistivity method. The real part (Reρ) and the imaginary part (Imρ) of the complex resistivity and permeability of coal were determined under different cycle times and in different bedding directions. The reason for permeability enhancement was discussed, and the dispersion mechanism of complex resistivity during cyclic freeze-thaw fracturing was analyzed. The results indicated that (1) the complex resistivity parameters have a good response to the cycle times; Reρ, |Imρ|, and the dispersion degree (α) are positively correlated with cycle time; the fully polarized frequency (f p) of Reρ, the characteristic frequency (f c) of Imρ, and variation are negatively correlated with cycle time. (2) The difference in complex resistivity parameters between the vertical bedding direction and the parallel bedding direction is significant, and the difference in electrical properties of the bedding structure continuously decreases with the increase in cycle time. (3) Under the effect of liquid nitrogen cyclic freeze-thaw, a complex network of fractures in coal is formed, the anisotropic characteristics of coal are weakened, and effective conductive channels are damaged. The peak frost heave force decreases exponentially with the increase in cycle time, and the difference in bedding electrical properties gradually disappears. (4) Comparing the inversion degree of measured data with three conductive models, ρ0 and τ are selected as the optimum parameters for evaluating the effect of liquid nitrogen cyclic freeze-thaw. A logarithmic permeability evaluation model is constructed based on ρ0 and τ. This work provides a new perspective based on electrical detection for evaluating the permeability enhancement of coal during liquid nitrogen cyclic freeze-thaw.

Development of a Superhydrophobic Protection Mechanism and Coating Materials for Cement Concrete Surfaces.

In order to further enhance the erosion resistance of cement concrete pavement materials, this study constructed an apparent rough hydrophobic structure layer by spraying a micro-nano substrate coating on the surface layer of the cement concrete pavement. This was followed by a secondary spray of a hydroxy-silicone oil-modified epoxy resin and a low surface energy-modified substance paste, which combine to form a superhydrophobic coating. The hydrophobic mechanism of the coating was then analysed. Firstly, the effects of different types and ratios of micro-nano substrates on the apparent morphology and hydrophobic performance of the rough structure layer were explored through contact angle testing and scanning electron microscopy (SEM). Subsequently, Fourier transform infrared spectroscopy and permeation gel chromatography were employed to ascertain the optimal modification ratio, temperature, and reaction mechanism of hydroxy-silicone oil with E51 type epoxy resin. Additionally, the mechanical properties of the modified epoxy resin-low surface energy-modified substance paste were evaluated through tensile tests. Finally, the erosion resistance of the superhydrophobic coating was tested under a range of conditions, including acidic, alkaline, de-icer, UV ageing, freeze-thaw cycles and wet wheel wear. The results demonstrate that relying solely on the rough structure of the concrete surface makes it challenging to achieve superhydrophobic performance. A rough structure layer constructed with diamond micropowder and hydrophobic nano-silica is less prone to cracking and can form more "air chamber" structures on the surface, with better wear resistance and hydrophobic performance. The ring-opening reaction products that occur during the preparation of modified epoxy resin will severely affect its mechanical strength after curing. Controlling the reaction temperature and reactant ratio can effectively push the modification reaction of epoxy resin through dehydration condensation, which produces more grafted polymer. It is noteworthy that the grafted polymer content is positively correlated with the hydrophobicity of the modified epoxy resin. The superhydrophobic coating exhibited enhanced erosion resistance (based on hydrochloric acid), UV ageing resistance, abrasion resistance, and freeze-thaw damage resistance to de-icers by 19.41%, 18.36%, 43.17% and 87.47%, respectively, in comparison to the conventional silane-based surface treatment.

Nitrogen removal performance of bioretention cells under freeze-thaw cycles: Effects of filler structure and microbial community

Cold climates have an adverse effect on the nitrogen-removal capacity of bioretention cells, especially during freeze-thaw cycles (FTCs). To explore the effects of FTCs on the nitrogen removal performance of bioretention cells, this research compared the effects of FTCs on the pore structure and microbial community composition of the filler, and analyzed the nitrogen removal performance of the bioretention cell before (RT), during (FTC) and after (RRT) FTCs. The results demonstrated that RRT filler had a much greater number of pores with equivalent diameter <500 μm than RT filler, and that RRT had a higher pore volume and pore density than RT. Microbial community analysis revealed that the diversity and richness of the microbial community in FTC were lower than in RT, and the relative abundance of Lacunisphaera, Pseudomonas, and Dokdonella decreased significantly. There was no significant difference in microbial community richness between RRT and RT, however RRT diversity was lower. RRT has a higher relative abundance of nitrifying bacteria (Subgroup_10, Bryobacter, etc.) than RT, but a lower relative abundance of denitrifying bacteria (Pseudomonas, Dokdonella, Arenimonas, etc.). The nitrogen removal efficiency of FTC was inhibited, resulting in a decrease of 13.0 ± 4.86%, 19.7 ± 9.17%, and 26.6 ± 1.74% in the removal rates of ammonia nitrogen(NH4+-N), nitrate nitrogen(NO3−-N), and total nitrogen(TN) when compared to RT, respectively. RRT improved nitrification and increased NH4+-N removal rate by 10.3 ± 2.69% compared to RT. However, because of denitrification inhibition, the nitrogen removal performance of RRT was not able to reach RT levels, and its NO3−-N and TN removal rates decreased by 100 ± 4.70% and 58.3 ± 3.71%, respectively. This study has demonstrated that FTCs can permanently harm the bioretention cell's filler structure and microbial community, resulting in a significant decrease in the nitrogen removal performance of the bioretention cell designed according to warm climate conditions after experiencing FTCs.

Elucidating the evolution of pore structure, microstructural damage, and micromechanical response in cement pastes containing microencapsulated phase change materials under freeze-thaw conditions

As climate variability intensifies the frequency and severity of freeze-thaw cycles, the development of cementitious materials capable of withstanding these harsh conditions becomes increasingly crucial. This research focuses on the potential of Microencapsulated Phase Change Materials (MPCMs) to enhance the durability of Hardened Cement Paste (HCP) in the face of such challenges. Specifically, this paper evaluates the influence of MPCMs on evolution of pore microstructure, damage, and micromechanical response in HCP subjected to extended freeze-thaw cycles, utilizing Low-Temperature Differential Scanning Calorimetry (LTDSC), X-ray Tomography (XRT), and micro-indentation. LTDSC results indicate a lower ice-crystallization temperature and a significant reduction in ice formation in MPCM-integrated HCP. Micro-indentation experiments reveal that while the control HCP undergoes substantial decreases in indentation hardness (35 %) and Young's modulus (37 %) after 180 cycles, the MPCM samples show much lower losses (only 9 % loss in hardness and 7 % loss in Young's modulus for 20 % MPCM inclusion). XRT image analysis reveals that MPCMs mitigate pore enlargement, preserve a stable pore size distribution, and effectively reduce the risk of increased interconnected porosity in HCP when subjected to extended freeze-thaw cycles. Crack analysis demonstrates that control HCP samples exhibit significant crack propagation with increased freeze-thaw cycles, while samples with 10 % MPCM inclusion show only slight crack initiation, and those with 20 % MPCM inclusion maintained their structural integrity with virtually no crack progression after 180 freeze-thaw cycles. These findings underscore the potential of MPCMs to improve the durability of HCP against freeze-thaw damage, offering key insights for designing more robust materials.

Dynamic compliance penis enlargement patch

Men are particularly sensitive to penis size, especially those with a deformed or injured penis. This can lead to a strong desire for penis enlargement surgery. Given the ethical sensitivities of the penis, penile implants need to be developed with both efficacy and safety. In this study, a polyvinyl alcohol (PVA) patch for penile enlargement prepared via cyclic freeze‒thaw cycles and alkaline treatment. The PVA hydrogels treated with 5 M NaOH had the best mechanical properties and stability. A negative Poisson's ratio structure is incorporated into the design of the enlargement patch, which allows it to conform well to the deformation of the penis. In rabbit models, the enlarged patches can effectively enlarge the penis without degradation or fibrosis while maintaining long-term stability in vivo. This innovation not only provides a safe option for patients in need of penile enlargement but also promises to make a broader contribution to the field of dynamic tissue repair.

Meat exudate metabolomics reveals the impact of freeze-thaw cycles on meat quality in pork loins

The aim of this study was to explore the effects of freeze-thaw (FT) cycles on meat quality, myofibrillar protein gelation and emulsification properties, and exudate metabolome changes in pork loins. Meat tenderness improved (P < 0.05), whereas water-holding capacity (WHC), meat color attributes declined (P < 0.05) with FT cycles. Multiple FT accelerated meat lipid and protein oxidations. Decreases in strength and WHC of myofibrillar protein gels with FT cycles were confirmed. Myofibrillar protein emulsions with more FT cycles showed a decrease in the emulsifying activity index (P < 0.001) and larger oil droplets, resulting in poorer storage stability. A total of 501 metabolites were tentatively identified in pork exudates, with 21 metabolites significantly correlated (P < 0.05 and r > 0.6) with meat quality attributes. These results demonstrated the potential of using the metabolomic information from exudates to elaborate on or even predict the FT cycles, or meat quality.

Case study on the relationship between transmission of antibiotic resistance genes and microbial community under freeze-thaw cycle on cold-region dairy farm

Freeze-thaw cycle (FTC) is a naturally occurring phenomenon in high-latitude terrestrial ecosystems, which may exert influence on distribution and evolution of microbial community in the soil. The relationship between transmission of antibiotic resistance genes (ARGs) and microbial community was investigated upon the case study on the soil of cold-region dairy farm under seasonal FTC. The results demonstrated that 37 ARGs underwent decrease in the abundance of blaTEM from 80.4 % for frozen soil to 71.7 % for thawed soil, and that sul2 from 8.8 % for frozen soil to 6.5 % for thawed soil, respectively. Antibiotic deactivation was identified to be closely related to the highest relative abundance of blaTEM, and the spread of sulfonamide resistance genes (SRGs) occurred mainly via target modification. Firmicutes in frozen soil were responsible for dominating the abundance of ARGs by suppressing the native bacteria under starvation effect in cold regions, and then underwent horizontal gene transfer (HGT) among native bacteria through mobile genetic elements (MGEs). The TRB-C (32.6–49.1 %) and tnpA-06 (0.27–7.5 %) were significantly increased in frozen soil, while Int3 (0.67–10.6 %) and tnpA-04 (11.1–19.4 %) were up-regulated in thawed soil. Moreover, the ARGs in frozen soil primarily underwent HGT through MGEs, i.e. TRB-C and tnpA-06, with increased number of Firmicutes serving as carrier. The case study not only demonstrated relationship between transmission of ARGs and microbial community in the soil under practically relevant FTC condition, but also emphasized the importance for formulating better strategies for preventing FTC-induced ARGs in dairy farm in cold regions.