Search Results (741)

Background/Objectives: Triglyceride (TG), Total Cholesterol (TC), HDL cholesterol (HDL-C), and LDL cholesterol (LDL-C) levels are commonly tested routine lipid profiles (RLPs) for assessing cardiovascular disease (CVD) risk. While lipid levels are typically measured by using standard clinical chemistry tests in routine practice, Nuclear Magnetic Resonance (NMR) spectroscopy has recently been explored for its ability to determine lipid levels under clinical settings. This study aims to compare RLP and NMR analysis using 17,337 fresh serum samples. Additionally, it investigates the impacts of freezing–thawing on these parameters in 9559 frozen samples. Methods: RLP was performed by employing the Siemens Dimension clinical chemistry system. Furthermore, the lipid contents of the fresh and frozen serum samples were evaluated across different concentration ranges. Results: Lipid parameters of fresh samples ascertained with RLP and NMR were strongly correlated (r ≥ 0.93). Analysis with frozen samples revealed that the correlation between lipid measurements decreased below r ≤ 0.86, except for TG (r = 0.97). Additionally, at different concentration ranges, the lower-level ranges for all lipid parameters in both fresh and frozen samples exhibited weaker correlations. Conclusions: This study demonstrates that NMR spectroscopy is a reliable, rapid, chemical-free method for lipid analysis in fresh samples. However, in frozen samples, relying on NMR to support RLP offers a less reliable approach for lipid measurement. Full article

This study uniquely explores the impact of a novel natural antifreeze peptide derived from grass carp (GCAFP) on the freeze–thaw characteristics and structural stability of wet gluten protein, providing new insights into the development of natural cryoprotectants for frozen foods. The effects of GCAFP on the physicochemical and structural properties of gluten protein were investigated using differential scanning calorimetry (DSC), nuclear magnetic resonance imaging (NMR), rheology, and scanning electron microscopy (SEM). The results showed that the addition of 0.5% GCAFP significantly reduced the freezing temperature (T_f, from −8.50 ± 1.31 °C to −10.75 ± 2.49 °C) and expanded the melting temperature range (T_m,δ, from 3.60 ± 1.40 °C to 5.65 ± 0.12 °C), indicating improved freezing stability. After five weeks of frozen storage, the ice crystal melting enthalpy (ΔH_m) of gluten protein in the GCAFP group increased by only 20.17 J/g, compared with 27.23 J/g in the control, representing a 6.35% reduction (p < 0.05). Similarly, after five freeze–thaw cycles, the freezable water fraction (F_w) and ΔH_m were reduced by 5.19% and 1.55%, respectively, demonstrating that GCAFP inhibited water migration and ice recrystallization. Low-field NMR revealed that GCAFP maintained a higher proportion of bound water (T21) and decreased free water (T23), confirming its role in restricting water mobility. Rheological analysis showed that GCAFP preserved the viscoelasticity of gluten protein, maintaining higher storage (G′) and loss (G″) moduli than the control after five freeze–thaw cycles, thus mitigating the decline in network elasticity. Structural characterization indicated that GCAFP stabilized the α-helix and β-sheet contents, reduced glutenin macropolymer depolymerization from 24.85% to 18.95%, and strengthened hydrogen bonding within the protein matrix. Overall, GCAFP effectively protected wet gluten protein against ice crystal damage by maintaining water distribution, viscoelasticity, and secondary structure integrity, highlighting its potential as a natural antifreeze ingredient for frozen food applications. Full article

Sludge bulking is a phenomenon that seriously affects the operation of activated sludge wastewater treatment plants (WWTPs). In this study, synthetic wastewater and a sequencing batch reactor (SBR) were employed to investigate the control of freeze–thaw on sludge bulking and the changes in sludge flora. The results observed that an imbalanced carbon–nitrogen–phosphorus ratio (C:N:P) in wastewater significantly increased the relative abundance of Thiothrix from 0.04% to 26.00%, while the sludge volume index (SVI) rose from 61 to 228 mL/g, leading to filamentous bulking. The bulking sludge was frozen at −40 °C for 7 days and then naturally thawed. After being reintroduced into the reactor, the relative abundance of Thiothrix rapidly decreased to 0.18%, and the sludge settling performance temporarily returned to normal, but it could not operate stably. Six days later, severe non-filamentous sludge bulking recurred. The relative abundance of Zoogloea increased markedly from 12.96% to 62.26%, and the SVI reached 260 mL/g. When the carbon source was replaced with glucose, the settling performance of the sludge eventually recovered. Studies have shown that the higher the content of extracellular polymer substances (EPSs) is, the worse the settling performance of sludge is. This study provides new technical ideas for the control of sludge bulking. Full article

Plant-based meat analogs, particularly those produced by high-moisture extrusion, are prone to quality deterioration during frozen storage due to poor freeze–thaw stability. This study aimed to develop a synergistic stabilization strategy for soy protein isolate (SPI)-based extrudates using glucose oxidase (GO), phytase (PA), and tamarind gum (TG). The effects of individual additives (GO, PA, TG) and their combination (GO + TG) were systematically evaluated over seven freeze–thaw cycles, with a pure soybean-protein meat analog (PSM) as a control. The results showed that repeated freeze–thaw cycles severely degraded the control groups, leading to reduced water-holding capacity (WHC), increased hardness, and color darkening. While all additives mitigated these changes, the GO + TG combination exhibited the most pronounced protective effect, maintaining the highest WHC (0.993 ± 0.000), optimal texture (hardness 66.0 ± 0.0 N, elasticity 3.7 ± 0.0 mm), and minimal color variation. Structural analyses revealed that GO + TG effectively suppressed protein oxidation, minimized sulfhydryl loss, preserved protein secondary and tertiary structures, and inhibited the conversion of immobilized water to free water. The synergistic mechanism is attributed to the formation of a dual-network structure, wherein GO enhances covalent cross-linking and TG provides steric stabilization. This study offers a practical and effective approach for enhancing the freeze–thaw stability of extruded plant-based meat products, with potential industrial applications. Full article

Background and Objectives: To evaluate the impact of gonadotropin-releasing hormone agonist (GnRHa) triggering compared to human chorionic gonadotropin (hCG) triggering on frozen–thawed and fresh embryo transfer outcomes in patients with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization (IVF). Materials and Methods: This retrospective cohort study analyzed 267 IVF cycles of 261 PCOS patients treated with GnRH antagonist protocols. Patients were divided into three groups: GnRHa-triggered frozen–thawed embryo transfer (ET) (n = 126), hCG-triggered frozen–thawed ET (n = 68), and hCG-triggered fresh ET (n = 73). Baseline characteristics, stimulation parameters, and cycle outcomes were compared between groups. A binary logistic regression analysis was established to identify independent predictors of clinical pregnancy. Results: The GnRHa-triggered group had significantly higher numbers of retrieved oocytes, mature (MII) oocytes, and fertilized oocytes compared to both hCG-triggered groups (p < 0.001). The number of obtained embryos and frozen embryos (good-quality embryos) was highest in the GnRHa group (p < 0.001). However, clinical pregnancy rates were comparable between the groups with a similar number and grade of transferred embryos (32.53%, 38.23%, and 32.87%, respectively). Multivariate regression analysis revealed that the grade of the transferred embryo was a significant predictor of clinical pregnancy (p = 0.034). Conclusions: This study provides insights into different triggering strategies for final oocyte maturation in PCOS patients. GnRH-agonist-triggered frozen–thawed cycles showed comparable clinical pregnancy outcomes to those of hCG-triggered cycles, with a potentially lower OHSS risk. The findings suggest that individualized triggering approaches based on patient characteristics and OHSS risk may be beneficial for PCOS patients undergoing IVF. Full article

Background: The placenta plays a fundamental role in supporting fetal development, with angiogenesis being crucial for establishing an efficient maternal–fetal interface. Epigenetic mechanisms, particularly DNA methylation, can regulate the expression of angiogenesis-related genes and may be influenced by Assisted Reproductive Technology (ART), including In Vitro Fertilization (IVF) with fresh or frozen-thawed embryo transfer (ET and FET, respectively) and egg donation (ED), all potentially affecting placental vascular development and pregnancy outcomes. The present study compared global DNA methylation levels and the expression of Vascular Endothelial Growth Factor (VEGF), Placental Growth Factor (PlGF), and Soluble Fms-Like Tyrosine kinase-1 (sFlt-1) in placentae from physiological pregnancies obtained using ART versus those spontaneously conceived. Methods: Placental biopsies were collected from 98 physiological singleton term pregnancies (CTRL n = 29, ET n = 23, FET n = 25, ED n = 21). Global DNA methylation (5-mC) was quantified by ELISA Easy Kit; VEGF, PlGF, sFlt-1 mRNA and protein levels were assessed by Real-Time PCR and ELISA, respectively. Results: Global DNA methylation was significantly increased in FET and ED placentae compared with CTRL and ET. PlGF mRNA expression was upregulated in all ART groups, although protein levels were elevated only in ED placentae compared to CTRL and ET groups. VEGF mRNA was increased in FET placentae compared to CTRL, while protein levels showed a non-significant upward trend across ART groups. No differences in sFlt-1 expression were observed. Clinically, ART pregnancies were associated with significantly lower birth weight compared to CTRL, though values remained within the physiological range, and placental efficiency was preserved. Conclusions: Hypermethylation in FET and ED placentae may act as an epigenetic “buffer,” stabilizing vulnerable genomic regions and supporting the expression of pro-angiogenic factors. This adaptive mechanism likely helps to preserve placental function and fetal viability despite ART-related stressors, thereby mitigating the potential impact on birth weight. Full article

This study investigated the impact of thawing methods on the roasting quality and flavor of reduced-salt marinated large yellow croaker to optimize processing protocols for frozen products. Three thawing methods, low-temperature thawing (LTT), room-temperature thawing (RTT), and flowing-water thawing (FWT), were systematically evaluated. Freshly marinated (FM) and non-thawed (WT) samples served as controls. Key parameters, including thawing efficiency, physicochemical properties, texture, color, sensory attributes, and volatile organic compounds (VOCs), were analyzed. The results showed that FWT achieved the fastest thawing (14.67 min), significantly outperforming RTT (32.57 min) and LTT (591 min) (p < 0.05). Moisture content and springiness remained stable across treatments (p > 0.05). For color parameters, lightness (L*), yellowness (b*), and browning index (BI) showed no significant variations (p > 0.05), while the total color difference (ΔE) was significantly affected by thawing methods (p < 0.05). FWT exhibited the lowest salt retention (3.49 g/100 g), a 18.8% reduction compared to WT (4.30 g/100 g). Texture analysis revealed that FWT samples maintained optimal hardness and chewiness, with sensory scores second only to WT. Volatile profiling identified distinct “thermal–oxygen–temporal” effects, referring to the respective influences of heating conditions, oxidative environments, and processing time on flavor compound formation. RTT and WT treatments significantly increased the relative 1-propanethiol and 5-methyl-2-furanmethanol (>10% increase) contents, respectively, and markedly reduced the 2-butanol levels (<0.3%) due to volatilization losses. GC-IMS and electronic nose analysis established a robust correlation network among three major VOC clusters (aldehydes/alcohols, esters/acid/sulfides, and ketones), with sensory scores showing strong positive correlations with the alkane- and aromatic-sensitive sensors (W5C/W1C) of the electronic nose (r > 0.90) and negative correlations with other sensors (r < −0.70). These findings demonstrate that FWT offers the best balance of efficiency, salt reduction, and sensory quality, making it a superior method for reduced-salt marinated large yellow croaker industrial applications. Full article

Background/Objectives: Serum progesterone (P) levels on the day of frozen–thawed embryo transfer (FET) appear to influence treatment success. Some studies suggest that low P levels may negatively affect pregnancy outcomes, whereas others report a detrimental impact of elevated p values. Although a threshold of 10 ng/mL is frequently cited as indicative of adequate luteal support, the optimal P cut-off on the FET day remains unclear. This study aims to identify a predictive serum p value above which pregnancy rates do not decline in artificial FET cycles. Methods: A retrospective cohort study comprising 236 women who underwent FET between November 2021 and July 2023 was conducted at the Center of Assisted Medical Procreation of Centro Materno-Infantil do Norte. Serum P levels were measured on the day of FET. Three analytical approaches were used in assessing the association between P levels and FET outcomes: (1) fixed threshold of 10 ng/mL; (2) stratification into quartiles (Q1 < 7.30; Q2: 7.30–10.26; Q3: 10.27–13.42; Q4 > 13.42 ng/mL); (3) optimal P cut-off derived from ROC analysis (9.34 ng/mL). Continuous variables were compared using T-test or One-Way ANOVA. Categorical variables were analyzed using Chi-square test or Fisher’s exact test. Associations between P levels and pregnancy outcomes were further examined using logistic regression. Results: Using the P threshold of 10 ng/mL, women with p < 10 ng/mL showed significantly lower positive β-hCG rates (p = 0.020), implantation rates (p = 0.002), and clinical pregnancy rates (CPRs) (p = 0.019). Quartile-based comparisons revealed no significant differences. Regarding the ROC-derived cut-off, women with p ≥ 9.34 ng/mL had significantly higher positive β-hCG rates (38.5% vs. 52.8%, p = 0.012), implantation rates (30.0% vs. 45.5%, p = 0.002), CPR (36.3% vs. 50.0%, p = 0.016), ongoing pregnancy rates (24.4% vs. 37.6%, p = 0.013), and live birth rates (24.4% vs. 37.6%, p = 0.013). p ≥ 9.34 ng/mL remained an independent predictor of improved pregnancy outcomes in multivariate analysis. Conclusions: Serum P levels ≥ 9.34 ng/mL on the day of FET were associated with significantly higher pregnancy success, supporting the relevance of center-specific P thresholds and suggesting potential benefit in individualized luteal phase support strategies. Full article

Partially frozen soil (PFS) is comprises of coexisting unfrozen water and ice within its pores at subzero temperatures. The review paper examines how unfrozen water content (UWC) and pore ice content interact during phase changes under near-freezing conditions, governed by microscopic thermodynamic equilibrium. Key theories describing why UWC persists (premelting, disjoining pressure) and the soil freezing characteristic curve (SFCC), along with measurement techniques, including the gravimetric approach to advanced nuclear magnetic resonance for characterization of water content. The influence of the water–ice phase composition on mechanical behavior is discussed, signifying pore pressure and effective stress. Various modelling approaches categorized into empirical SFCC, physio-empirical estimations, and emerging machine learning and molecular simulations are evaluated for capturing predictions in PFS behavior. The relevance of PFS to infrastructure foundation, tailings dams, permafrost slope stability, and climate change impacts on cold regions’ environmental geotechnics is also highlighted as a challenges in practical application. Hence, understanding pore pressure dynamics and effective stress in PFS is critical when assessing frost heave, thaw weakening, and the overall performance of geotechnical structures in cold regions. By combining micro-scale phase interaction mechanisms and macro-scale engineering observations, this review paper provides a theoretical understanding of the underlying concepts vital for future research and practical engineering in cold regions. Full article

The paper explored the impact of sodium caseinate (CAS) emulsion on the freeze–thaw stability of konjac glucomannan (KGM)/κ-carrageenan (KC) composite gels. It found that the emulsion and KGM both increased the viscoelasticity of the composite gel, giving it a greater elastic stress. Emulsion addition enhanced the water-holding capacity (WHC) of the KC gel from 72.36% to 89.34%. KGM addition further improved WHC to 97.54%. The hardness of the emulsion KGM/KC gel reached 9.35 N, while the values were essentially not affected by freeze–thaw. This study shows that CAS emulsion, especially under the regulation of KGM and KC, can improve the freeze–thaw stability of the gel system. The results show that emulsion has great potential in regulating the physical and textural properties of multiphase gels. The emulsion coupling method could effectively enhance the freeze–thaw stability of gels, which may provide a new strategy for the development of frozen multiphase gel foods. Full article

This study investigated the impacts of different lipids (liquid oils: corn, peanut, soybean, rapeseed; solid fats: butter, shortening, margarine, lard, coconut oil) on the quality of frozen dough and bread. By comparing F0 (no freeze–thaw) and F2 (two freeze–thaw cycles), the impacts on dough texture, rheology, water distribution, differential scanning calorimetry (DSC), infrared analysis, microstructure, and baking performance were assessed. After F2, corn oil and peanut oil mitigated the increase in hardness. Solid fats better preserved dough viscoelasticity and bound water, thereby minimizing ice recrystallization and structural damage and achieving higher sensory scores, whereas liquid oils reduced the hardness of frozen bread and increased specific volume. Overall, liquid oils and solid fats displayed complementary advantages. This study offers innovative insights and practical value for the frozen-bakery food industry. Full article

Cryopreservation of stallion spermatozoa remains a challenge in equine reproduction, as it induces mitochondrial dysfunction that cannot be fully captured by conventional sperm quality assessment and requires further investigation. This study provides a detailed bioenergetic evaluation of cryopreserved stallion sperm using Seahorse XFp technology to measure basal oxygen consumption rate (OCR) and to perform a MitoStress Test. Three ejaculates from 20 Warmblood stallions (licensed by the Holsteiner Verband, Elmshorn, Germany) were analyzed at 15 min intervals from 15 to 120 min after thawing. CASA and multiparametric flow cytometry were used to assess motility, sperm viability, reactive oxygen species (ROS) synthesis, lipid peroxidation (LPO), and DNA fragmentation index (%DFI). Seahorse analysis revealed marked intra- and inter-individual variability in basal OCR among frozen–thawed samples. Functional mitochondrial parameters showed only partial correlations with motility and viability results, underlining the added diagnostic value of combined metabolic profiling. Over the 2 h measurement, viability and motility displayed an increasingly negative correlation with ROS synthesis, while no significant relation was found between OCR and ROS synthesis or LPO. These findings demonstrate that stallion sperm mitochondria are highly sensitive organelles whose functional state cannot be fully assessed by routine motility or viability testing alone. Integrating Seahorse-based profiling with CASA and flow cytometry can improve sperm quality assessment. Moreover, this novel approach has been proven to be a valuable tool, offering broad opportunities for further research in stallion reproduction. Full article

This work sought to test the positive effect of red LED light on frozen bovine sperm resistance to thawing in suboptimal conditions. Moreover, a preliminary study explores whether this improvement could have any repercussions on in vivo fertilizing ability. Thus, frozen bull semen straws (n = 16) were thawed (a) with irradiation for 5 min at 20 °C (2 min light, 1 min darkness, 2 min light; PHOTO); (b) without irradiation for 5 min at 20 °C (ET); or (c) through immersion into a water bath at 38 °C for 40 s as standard control (CONTROL). Sperm quality and preliminary, purely descriptive AI trials were performed. The PHOTO samples demonstrated significantly (p < 0.05) improved percentages of intact acrosomes, progressive motility, DNA condensation and fragmentation, and viable sperm with high ROS/superoxides. The viability of PHOTO samples decreased significantly (p < 0.05) when compared with the ET ones. Overall results of both the PHOTO and ET samples were poorer than those of the CONTROL. Otherwise, the PHOTO straws yielded greater pregnancy rates (64.0% vs. 49.4% in CONTROL) when evaluated at two different farms. The results suggest that irradiating cryopreserved bovine sperm during thawing in suboptimal conditions could improve AI pregnancy rates, although more in vivo studies are needed to support this conclusion. Full article

This study investigated the physicochemical properties and nutrient dynamics on the Romanian shelf of the northwestern Black Sea in July 2024, collecting data across 36 stations (13–1116 m depth) heavily influenced by Danube discharges. Vertical CTD profiling revealed a pronounced seasonal thermocline and a deep-lying permanent halocline. The Cold Intermediate Layer (CIL) boundary, defined by the 8 °C isotherm, was absent, indicating warmer subsurface waters. Surface nutrient concentrations, particularly for nitrate (NO₃) and phosphate (PO₄), were considerably lower than peak eutrophication periods, approaching pre-1970s values, suggesting a positive trend due to reduced anthropogenic loading. They are also comparable to or lower than other coastal regions in the Black Sea. Vertical nutrient profiles confirmed the typical anoxic Black Sea structure, but with regional specifics: the PO₄ maximum was slightly deeper, and the NO₃ maximum position and concentration mirrored the pre-eutrophication period, further supporting reduced anthropogenic nitrogen input. Silicate (SiO₄) concentrations were consistently low throughout the water column, suggesting the northwest shelf functions as a SiO₄ sink compared to the southeastern Black Sea. Overall results indicate a shift towards a less eutrophic state on the Romanian shelf while highlighting the continued dominance of Danube-driven hydrodynamics. In addition to those investigations, this study assessed nutrient preservation techniques, finding that pasteurization was significantly superior to freezing for maintaining the stability of PO₄ and NOx (losses up to 20% and 47% for frozen samples, respectively) over six months. Though SiO₄ was stable under both methods, the freezing produced lower concentrations, possibly from incomplete depolymerization during thawing. These findings stress that pasteurization could be taken into consideration as a reliable preservation technique for long-term storage of nutrient samples. Full article

The soil freeze–thaw process is a dominant disturbance in the seasonally frozen ground and the active layer of permafrost, which plays a crucial role in the surface energy balance, water cycle, and carbon exchange and has a pronounced influence on vegetation phenology. This study proposes a novel density-based Freeze–Thaw Disturbance Index (FTDI) based on the identification of the freeze–thaw disturbance region (FTDR) over the Qinghai–Tibet Plateau (QTP). FTDI is defined as an areal density metric based on geomorphic disturbances, i.e., the proportion of FTDRs within a given region, with higher values indicating greater areal densities of disturbance. As a measure of landform clustering, FTDI complements existing freeze–thaw process indicators and provides a means to assess the geomorphic impacts of climate-driven freeze–thaw changes during permafrost degradation. The main conclusions are as follows: the FTDR results that are identified by the random forest model are reliable and highly consistent with ground observations; the FTDRs cover 8.85% of the total area of the QTP, and mainly in the central and eastern regions, characterized by prolonged freezing durations and the average annual ground temperature (MAGT) is close to 0 °C, making the soil in these regions highly susceptible to warming-induced disturbances. Most of the plateau exhibits low or negligible FTDI values. As a geomorphic indicator, FTDI reflects the impact of potential freeze–thaw dynamic phase changes on the surface. Higher FTDI values indicate a greater likelihood of surface thawing processes triggered by rising temperatures, which impact surface processes. Regions with relatively high FTDI values often contain substantial amounts of organic carbon, and may experience delayed vegetation green-up despite general warming trends. This study introduces the FTDI derived from the FTDR as a novel index, offering fresh insights into the study of freeze–thaw processes in the context of climate change. Full article