Search Results (243)

Solid waste-based cementitious materials (SWCMs) represent an innovative class of binders derived mainly from construction and demolition waste as well as industrial byproducts. Their application in recycled mortar offers a promising pathway to partially replace conventional cement, thereby advancing resource recycling and facilitating a low-carbon transition in the cement industry. This review systematically examines the properties, activation techniques, strength development, and corrosion resistance of recycled mortar prepared with SWCMs. Recycled powder (RP) and industrial solid waste have gelation potential, but their low reactivity requires activation treatment to enhance utilization efficiency. Activation methods, including thermal activation, carbonation, and alkali activation, effectively enhance reactivity and promote the formation of dense gel structures (e.g., C-(A)-S-H, N-A-S-H). While low replacement ratios optimize pore structure via the microfiller effect, higher ratios introduce excessive inert components, impairing mechanical properties. SWCMs demonstrate superior resistance to sulfate and chloride attacks, but their acid resistance is relatively limited. They also have excellent freeze–thaw resistance. SWCMs represent a viable and sustainable alternative to conventional cement, exhibiting commendable mechanical and durability properties when properly activated and formulated, thereby contributing to resource recycling and environmental sustainability in the cement industry. Full article

Background: Inactivated enterovirus 71 (EV71) vaccines play a vital role in preventing severe cases of hand, foot, and mouth disease, with their quality and stability determined by the degree of viral particle aggregation. Objective: This study aimed to use dynamic light scattering (DLS) for monitoring EV71 particle size, comprehensively evaluate the effects of environmental stresses on viral aggregation, and identify suitable stabilizing agents. Methods: The DLS technique was validated. Using this method, the effects of pH, ionic strength, freeze–thaw cycles, temperature, and mechanical stresses on viral particle size were assessed. Additionally, the ability of different buffer salts and stabilizers to inhibit stress-induced aggregation was systematically evaluated. Results: The DLS method exhibited robust performance. EV71 particles were stable at pH 7.0–7.5. Exposure to 47 °C and magnetic stirring promoted viral aggregation. Phosphate buffer and citrate buffer exhibited the highest inhibitory effects on heat-induced aggregation and stirring-induced aggregation, respectively. M199 and Tween 80 efficiently mitigated heat-induced particle aggregation and shear stress-induced particle aggregation, respectively. Conclusions: This study demonstrated the performance of DLS in viral aggregation monitoring. Additionally, this study revealed tailored stabilization strategies, providing key insights for vaccine formulation and quality control. Full article

Cryopreservation is a crucial technique for the long-term preservation of swine genetic resources. However, its efficiency remains limited by cryo-induced oxidative stress, which compromises sperm membrane integrity, mitochondrial function, and fertilizing capacity. Methyl gallate (MG), a naturally occurring polyphenolic antioxidant, has demonstrated strong free radical scavenging and lipid peroxidation inhibitory properties. This study aimed to evaluate the effects of MG supplementation on sperm quality and fertilization capacity during boar semen cryopreservation. Semen samples were cryopreserved in extenders containing different concentrations of MG (0, 10, 20, 30, and 50 µM). Post-thaw sperm quality, oxidative status, mitochondrial activity, apoptosis-related markers, and in vitro fertilization (IVF) outcomes were comprehensively assessed. The results showed that supplementation with 20 µM MG significantly improved post-thaw motility, viability, membrane and acrosome integrity, mitochondrial membrane potential, ATP content, and antioxidant capacity, while decreasing reactive oxygen species (ROS) and malondialdehyde (MDA) levels and reducing apoptosis (p < 0.05). Moreover, the expression of the anti-apoptotic protein BCL-2 was upregulated, whereas that of the pro-apoptotic protein BAX was downregulated. Sperm cryopreserved with 20 µM MG also exhibited a significantly higher IVF cleavage rate compared with the control group (p < 0.05). In conclusion, MG supplementation effectively enhanced boar sperm cryosurvival by maintaining membrane stability, improving mitochondrial function, and mitigating oxidative stress during freezing and thawing. These findings suggest that MG is a promising antioxidant additive for improving the efficiency of boar semen cryopreservation systems. Full article

Partially frozen soil (PFS) is composed of coexisting unfrozen water and ice within its pores at subzero temperatures. This 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. We present 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 infrastructural foundations, tailing dams, permafrost slope stability, and climate change’s impacts on cold regions’ environmental geotechnics is also highlighted as a challenge 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

This study examines the synergistic influence of recycled concrete aggregates (RCAs), industrial steel fibers (ISFs), recycled steel fibers (RSFs), and hybrid ISF/RSF (HSF) on the structural, durability, and environmental performance of roller-compacted concrete pavement (RCCP). Twenty mixtures were prepared with 0 and 50% RCA and fiber dosages of 0–0.9%, including plain, single-fiber, and HSF systems. Compressive, splitting tensile, and flexural strengths, as well as freeze–thaw resistance up to 300 cycles, were experimentally evaluated. Environmental performance was quantified through a cradle-to-gate life cycle assessment (LCA) covering nine impact categories and integrated with a multi-criteria decision analysis (MCDA) using the weighted sum method (WSM) and technique for order of preference by similarity to ideal solution (TOPSIS). Results indicate that 50% RCA replacement reduced compressive strength by ~21% but decreased global warming potential (GWP) by 15%. Hybrid fiber reinforcement significantly improved mechanical and durability properties, achieving up to 51% higher tensile strength and >85% strength retention after 300 freeze–thaw cycles compared with the control mix. The LCA showed notable reductions in GWP, acidification potential, and non-renewable energy demand when ISF and natural aggregates were partially substituted with RSF and RCA. The MCDA identified N50_R50_ISF0.3_RSF0.3 (50% RCA with 0.6% HSF) as the optimal mixture, achieving the highest eco-efficiency index (WSM = 0.80; TOPSIS = 0.73). These findings confirm that integrating RCA with hybrid steel fibers enhances the mechanical and durability performance of RCCP while substantially reducing environmental burdens, providing a viable strategy for low-carbon and circular pavement construction. 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

In situ physical coal fracturing is one of the key technologies for deep coal resource extraction, among which the liquid nitrogen cyclic freeze–thaw (LNCFT) technique demonstrates remarkable fracturing effects and promising application potential in physical coal breaking. To determine economically viable mining and coalbed methane (CBM) extraction cycles, this study builds on previous research and conducts a series of experiments to investigate the effects of different cold condition temperatures and freeze–thaw cycles on the mesoscopic surface structure and macroscopic mechanical properties of deep, water-rich coal-rock samples. A statistical damage constitutive model for saturated coal-rock under coupled freeze–thaw and loading, incorporating a damage threshold, was established to more accurately describe the damage patterns and mechanisms. The results indicate that lower cold condition temperatures lead to greater mesoscopic crack propagation, lower uniaxial compressive strength, and significantly reduced freeze–thaw failure cycles. Under −45 °C, saturated coal-rock samples experienced macroscopic failure after only 23 freeze–thaw cycles, which is 9 and 15 cycles fewer than those under −30 °C and −15 °C, respectively. Furthermore, measurements of wave velocities in three directions before and after testing revealed that freeze–thaw cycles caused particularly pronounced damage in the direction perpendicular to the bedding planes. Additionally, the established coupled statistical damage constitutive model provides a more accurate and intuitive analysis of the entire process from damage to failure under different cold conditions, showing that as the temperature decreases and freeze–thaw cycles increase, the coal-rock’s brittleness diminishes while plastic deformation and ductile failure characteristics are enhanced. In summary, for coal and CBM extraction using the LNCFT technique, it is recommended to extract gas once after approximately 35 cycles of liquid nitrogen injection. This study provides a theoretical basis for the application of liquid nitrogen cyclic freeze–thaw technology in deep coal fracturing. Full article

Sperm cryopreservation is a key technique in assisted reproductive technologies (ART), livestock breeding, fertility preservation, and wildlife conservation. However, the freeze–thaw process induces significant oxidative stress through the production of reactive oxygen species (ROS) by mitochondria, which can lead to impaired sperm motility, membrane damage, DNA fragmentation, and reduced fertilization potential. MitoQ is a mitochondria-targeted antioxidant consisting of a ubiquinone moiety conjugated to triphenylphosphonium (TPP⁺). MitoQ selectively accumulates in the mitochondrial matrix, where it efficiently scavenges reactive oxygen species (ROS) at their point of origin. This targeted action helps preserve mitochondrial function, sustain ATP production, and inhibit apoptotic signaling. Extensive experimental evidence across diverse species, including bulls, rams, boars, humans, dogs, and goats, shows that MitoQ supplementation during cryopreservation enhances post-thaw sperm viability, motility, membrane integrity, and DNA stability. Optimal dosing between 50 and 150 nM achieves these benefits without cytotoxicity, although higher doses may paradoxically increase oxidative damage. Compared to conventional antioxidants, MitoQ offers superior mitochondrial protection and enhanced preservation of sperm bioenergetics. Future directions involve exploring synergistic combinations with other cryoprotectants, advanced delivery systems such as nanoparticles and hydrogels, and detailed mechanistic studies on long-term effects. Overall, MitoQ represents a promising adjunct for improving sperm cryopreservation outcomes across clinical, agricultural, and conservation settings. Full article

Consisting of phospholipids, sperm membranes surround the head and tail, playing essential roles in maintaining cellular structural integrity and functions. Their characteristics directly influence sperm fertility and cryopreservation outcomes. This minireview provides a summary of how sperm fertility and freezability are affected by the characteristics of its cell membranes. The primary emphasis is on the molecular and cellular anatomy as well as the physiology of sperm membranes and their attributes associated with fertility determinants or biomarkers for fertility and freezability. It also explores how this knowledge can guide the development of extenders to improve sperm freezability and enhance reproductive technologies in mammals. By providing integrity, fluidity, and selective permeability, the membranes play vitally important roles in sperm motility, which is required for successful fertilization. Cryopreservation, which involves freezing and thawing of sperm for storage or ART, alters the integrity and functionality of the sperm membranes. Sperm freezability, its viability following freezing and thawing, is influenced by several properties of the sperm cell membranes, such as lipid composition, cholesterol content, and structures and functions of the membrane proteins. This review provides concise information about the nature of sperm membranes. It highlights the importance of understanding specific biophysical and biochemical features, including lipid composition, protein distribution, and membrane phase behavior. Particular attention is given to parameters such as the cholesterol–phospholipid ratio and membrane phase transition temperature (Tm). A deeper understanding of these factors can contribute to the identification of reliable fertility biomarkers and the optimization of cryopreservation techniques used in ART and animal breeding programs. Furthermore, this review underscores the need for comprehensive investigations into the molecular and cellular architecture of sperm cells. Such studies are essential for advancing both fundamental and applied aspects of reproductive biology in food-producing animals, endangered species, and humans. Full article

Cementitious materials are multiscale and multiphase composites whose frost resistance at the macroscale is closely governed by microstructural characteristics. However, the interfacial transition zone (ITZ) between clinker and hydrates, recognized as the weakest solid phase, plays a decisive role in the initiation and propagation of microcracks under freezing conditions. Understanding the frost damage mechanism of ITZ is therefore essential for improving the durability of concrete in cold regions. The motivation of this study lies in revealing how freezing affects the mechanical integrity and microstructure of ITZ in its early ages, which remains insufficiently understood in existing research. To address this, a nanoscratch technique was employed for its ability to quantify local fracture properties and interfacial adhesion at the submicronscale, providing a direct and high-resolution assessment of ITZ behavior under freeze–thaw action. The ITZ thickness and fracture properties were characterized in unfrozen cement paste and in cement paste frozen at 1 and 7 days of age to elucidate the microscale frost damage mechanism. Moreover, the enhancement effect of nano-silica modification on frozen ITZ was investigated through the combined use of nanoscratch and mercury intrusion porosimetry (MIP). The correlations among clinker particle size, ITZ thickness, and ITZ fracture properties were further established using nanoscratch coupled with scanning electron microscopy (SEM). This study provides a novel micromechanical insight into the frost deterioration of ITZ and demonstrates the innovative application of nanoscratch technology in characterizing freeze-induced damage in cementitious materials, offering theoretical guidance for designing durable concrete for cold environments. Full article

Background: Cadaveric specimens used in research are commonly frozen when stored and may undergo multiple freeze–thaw cycles during experimental procedures. To streamline workflows and minimize potential tissue degradation from repeated thawing, this study evaluated whether a frozen cadaver wrist can be reliably used to model a scaphoid for the development of a patient-specific prosthesis design method in a preclinical setting. Additionally, we assessed the impact of segmentation smoothing techniques on the accuracy of the prosthesis model. Methods: High-resolution computed tomography (CT) scans were performed on a cadaver wrist in both frozen and thawed states. Scaphoid bones were segmented using two approaches: a tight (native surface) segmentation and a smoothened version optimized for prosthetic articulation. The resulting 3D models were registered, and volume and shape differences between frozen and thawed states, as well as between segmentation methods, were quantified. Results: No statistically significant volume differences were observed between scaphoid models segmented from frozen and thawed conditions (p = 0.46). The average difference was 0.14% (SD 0.55). Furthermore, smoothing segmentation had minimal impact on the overall dimensions of the scaphoid model. Conclusions: Frozen cadaver wrists can be used to accurately model scaphoid bones for patient-specific prosthesis design without introducing significant volumetric deviations. Segmentation smoothing, which is necessary for prosthesis fabrication, does not compromise anatomical accuracy, supporting the feasibility of using frozen specimens for preclinical modeling. Full article

In the preparation of rubber-recycled cement mortar (RRCM), recycled fine aggregates (RFA) were used to replace 95% of natural fine aggregates (NFA) by mass, with an additional 5% of NFA replaced by rubber particles (RP). Additionally, nano-silica (NS) was incorporated to replace ordinary Portland cement (OPC) by mass at a replacement of 0%, 1%, 2%, 3%, and 4%. The study aimed to investigate the effects of NS on the mechanical properties, freeze–thaw resistance, and microstructure of RRCM, using techniques such as X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM) to reveal the enhancement mechanisms. The results indicated that the compressive strength and flexural strength of RRCM at 28 days decreased by 10.3% and 10.1%, respectively, compared to NCM. After adding 1–3% NS, the mechanical properties of RRCM were improved, with the enhancements increasing as the NS content increased. Specifically, RRCM3 exhibited a 7.7% and 7.6% improvement in compressive and flexural strength, respectively, compared to RRCM0. After 30 freeze–thaw cycles, the strength loss rate of RCM was 27.51%, whereas the strength loss rate of RRCM3 was reduced to 20.13%, with better overall appearance integrity. Moreover, NS promoted the hydration of cement; reduced the contents of tricalcium silicate (C₃S), and dicalcium silicate (C₂S) and calcium hydroxide (CH); and facilitated the formation of additional hydration products that filled the interfacial transition zone (ITZ). The incorporation of 3% NS was found to provide the optimal improvement in RRCM. Full article

Electrospun fibers serve as a medium for the targeted release of active compounds, facilitating the desired therapeutic effects in drug administration. The point of this study was to find the best conditions for making electrospun fibers from cellulose acetate (CA) and poly(ε-caprolactone) (PCL), mixed with pure oxyresveratrol extract from Artrocarpus lakoocha Roxberg (Moraceae). Additionally, the study focused on evaluating the antioxidant properties, antityrosinase activity, and freeze–thaw stability of the resulting fibers. We incorporated a concentration of oxyresveratrol at 0.1% w/w into various mass ratios of CA/PCL blended fiber sheets (1:0, 3:1, 1:1, 1:3), utilizing mixed solvents of acetone/DMF (2:1% v/v) and chloroform/DMF (9:1% v/v) for preparation. The fiber sheets displayed a continuous and uniform structure, with fiber diameters ranging from 300 to 1000 nanometers. We investigated the release kinetics of oxyresveratrol from the fibrous substrates using the total immersion technique, specifically in phosphate-buffered saline at a pH of 7.4. The results showed that the fiber sheet with a 3:1 w/w ratio of CA to PCL and a 0.1 w/w loading of oxyresveratrol showed the most significant release of oxyresveratrol at the 2 h mark, and it continued to release consistently at this peak value for up to 24 h. The antioxidant and anti-tyrosinase properties of oxyresveratrol in fiber sheets were more stable than those of free oxyresveratrol at the same concentrations. The fiber sheet presents a promising avenue for a user-friendly transdermal patch application. Full article

The cryopreservation of Chengde polled goat semen plays a critical role in conserving genetic resources, enhancing the utilization efficiency of superior breeding bucks, and advancing artificial insemination techniques. However, spermatozoa are vulnerable to oxidative stress during the freezing process, which can significantly compromise sperm motility. In this study, pooled ejaculates from multiple bucks were divided into six groups, including a control group cryopreserved with conventional extender and five treatment groups supplemented with sericin at concentrations of 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% (w/v). The results demonstrated that supplementation of the semen cryoprotectant with 0.6% sericin significantly improved post-thaw sperm viability to 65.25% in Chengde hornless goats, while concurrently reducing both the sperm abnormality rate (p < 0.05) and intracellular ROS levels (p < 0.05). Integrated TMT proteomics and LC/MS metabolomics further compared the 0.6% sericin group with the frozen control group and identified 162 differentially expressed proteins and 109 differential metabolites between the sericin supplementation and frozen control groups. Functional analysis revealed the significant enrichment of differential metabolites, such as glutamine, in the alanine, aspartate, and glutamate metabolism pathway, concomitant with the marked upregulation of antioxidant proteins including LRP8, GSTM3, and SIRT2. Thus, 0.6% sericin enhances cryotolerance primarily by improving sperm viability, reducing oxidative damage, and sustaining energy metabolism. These findings indicate that sericin enhances cryotolerance by reducing oxidative damage and supporting metabolic function, providing preliminary molecular insights for improving goat semen cryopreservation. Full article

This review provides a comprehensive examination of porosity and permeability as key parameters governing the durability and performance of construction materials, including natural stone, mortar, concrete, and other cementitious composites. It highlights the pivotal role of pore structure in transport phenomena and degradation mechanisms, examining how the variations in pore architecture, encompassing total vs. effective porosity, pore size distribution, and pore connectivity, dictate a material’s response to environmental stressors. A comparative evaluation of advanced pore characterization techniques is presented, including helium pycnometry, mercury intrusion porosimetry (MIP), nitrogen adsorption (BET/BJH), nuclear magnetic resonance (NMR) relaxometry, and imaging methods such as optical microscopy, scanning electron microscopy (SEM), and X-ray micro-computed tomography (micro-CT). Furthermore, it assesses how these porosity and permeability characteristics influence durability-related processes like freeze–thaw cycling, chloride ingress, sulphate attack, and carbonation. Case studies are discussed in which various additives have been employed to refine the pore structure of cement-based materials, and pervious concrete is highlighted as an example where deliberately high porosity and permeability confer functional benefits (e.g., enhanced drainage). Overall, these insights underscore the importance of tailoring porosity and permeability in material design to enhance durability and sustainability in construction engineering. Full article