Search Results (859)

We report on X-ray-induced Sm³⁺ → Sm²⁺ reduction in SrF₂:Sm³⁺ nanocrystals of ~40 nm size synthesized via a co-precipitation method. Non-irradiated samples show characteristic Sm³⁺ f-f ⁴G_5/2 → ⁶H_5/2, ⁶H_7/2, ⁶H_9/2, and ⁶H_11/2 emissions, while X-irradiation induces intense low-temperature Sm^{2+ 5}D₀ → ⁷F₁ emission and other Sm²⁺ lines. The evolution of Sm³⁺ and Sm²⁺ photoluminescence intensities with X-ray dose (0–300 Gy) follows first-order kinetics, consistent with a trapping–detrapping mechanism. Compared to CaF₂:Sm³⁺, SrF₂:Sm³⁺ exhibits faster Sm³⁺ reduction due to the higher X-ray absorption cross section of strontium compared to calcium for Cu-Kα (8 keV) radiation, highlighting its potential as a nanoscale X-ray storage phosphor. Full article

Strontium (Sr) is an essential trace element that plays a critical role in bone health, calcium absorption, cardiovascular function, and nerve function. In this experiment, fresh-cut peaches were treated with different concentrations of strontium chloride (SrCl₂) to study the effects of SrCl₂ on the antioxidant system, endogenous nitric oxide (NO) metabolism, and endogenous hydrogen sulfide (H₂S) metabolism, aiming to investigate the regulatory mechanism of Sr on postharvest quality of horticultural products. The results showed that, compared with the control, 320 μM SrCl₂ significantly suppressed the respiration rate by 15.10% and delayed the respiratory peak by 2 days. Meanwhile, SrCl₂ treatment effectively inhibited the rise in electrolyte leakage (EL), color difference, and weight loss, and delayed the decline in fruit firmness. In addition, SrCl₂ treatment significantly up-regulated the gene expression levels and enzyme activities of the antioxidant system, the AsA-GSH cycle, NO, and H₂S metabolism, which reduced the loss of antioxidants, enhanced the ability of fruits to scavenge hydrogen peroxide (H₂O₂), hydroxyl radical (˙OH), and superoxide anion (O₂⁻˙), and lowered the malondialdehyde (MDA) content. It suggests that SrCl₂ treatment has a positive effect on maintaining the postharvest quality of fresh-cut peaches, which appears to be associated with increased endogenous production of NO and H₂S, thereby enhancing antioxidant system activity. Full article

This study investigates the effect of a 30 wt.% solid-content colloidal nano-silica (CNS) suspension, incorporated at 0–6 wt.% of cement, on the early-age (7 and 14 days) and later-age (28 and 56 days) compressive strength and microstructure of pumice aggregate lightweight concrete (PALC). The corresponding effective solid nano-silica content ranges from 0 to 1.8 wt.% of cement. Compressive strength increased with CNS dosage up to 5 wt.%, after which a plateau behavior was observed. At 7 days, compressive strength increased from 19.93 MPa to 26.81 MPa, corresponding to an improvement of approximately 34.5%. Although the 6 wt.% mixture showed slightly higher strength at early age, this trend was not sustained at later ages. The highest compressive strength at 56 days was obtained at 5 wt.% CNS (39.68 MPa), with a slight decrease at 6 wt.% CNS. X-ray diffraction (XRD) analysis indicated a reduction in calcium hydroxide (CH) peak intensity with increasing CNS content, suggesting the occurrence of pozzolanic reactions; however, this interpretation remains qualitative. Scanning electron microscopy (SEM) observations revealed a denser and more homogeneous matrix structure at 5 wt.% CNS, corresponding to improved mechanical performance. Slump values decreased from 9.0 cm to 6.6 cm with increasing CNS dosage, indicating reduced workability, while water absorption values slightly decreased from 18.51% to 17.20%. Full article

Gypsum-based fire protection relies on thermally activated dehydration, where chemically bound water is released and evaporated, thereby providing an endothermic heat sink that delays heat penetration through assemblies. In parallel, inorganic hydrated salts are increasingly used as flame-retardant additives in gypsum-based systems to enhance heat absorption over specific temperature ranges. Fire simulation tools and performance-based fire engineering approaches require reliable kinetic data and reaction enthalpies that can be implemented as coupled thermal–chemical source terms. However, additive-specific kinetic datasets remain limited, particularly under restricted vapor exchange conditions representative of porous construction materials. This work investigates the thermal decomposition behavior and dehydration kinetics of Aluminum Trihydrate (Al(OH)₃, ATH), Magnesium Hydroxide (Mg(OH)₂, MDH), Calcium Aluminate Sulfate (3CaO·Al₂O₃·3CaSO₄·32H₂O, CAS), and Magnesium Sulfate Heptahydrate (MgSO₄·7H₂O, ESM) with emphasis on vapor-restricted conditions representative of confined porous systems. Differential scanning calorimetry (DSC) experiments were conducted at three heating rates (2, 10, and 20 K/min for MDH, CAS and ESM and 20, 40 and 60 K/min for GB-ATH) up to 600 °C using pinhole crucibles to simulate autogenous vapor pressure. The thermal analysis indicates that ATH and MDH exhibit predominantly single-step dehydration behavior, while ESM shows a complex multi-step mechanism. Although CAS presents a single dominant thermal peak in the DSC signal, the isoconversional analysis reveals a multi-stage reaction behavior, demonstrating that peak-based interpretation alone may be insufficient for such systems. Kinetic parameters were determined using both model-free (Starink) and model-fitting approaches in accordance with the recommendations of the Kinetics Committee of the International Confederation for Thermal Analysis and Calorimetry (ICTAC). All reactions were consistently described using the Avrami–Erofeev model as an effective phenomenological representation of the conversion behavior. The extracted kinetic triplets were validated through numerical simulations, showing good agreement with experimental conversion and reaction rate data. The resulting kinetic parameters and dehydration enthalpies provide a physically consistent dataset for the description of dehydration processes under restricted vapor exchange. These results support the development of thermochemical models for gypsum-based systems; however, their transferability to full-scale assemblies remains subject to validation under coupled heat- and mass-transfer conditions. Full article

The increasing demand for different value-added products from natural seaweeds requires a sustainable cultivation method for the regular supply of biomass and to safeguard the natural ecosystem from overexploitation. This study evaluated laboratory acclimatization of the green seaweed Acrosiphonia orientalis (DGR: 2.71 ± 0.21%; GPP: 12.55 ± 0.1 mg O₂ L⁻¹ day⁻¹), followed by a comparative evaluation of its physicochemical and biochemical characteristics, metabolite profile, and antiproliferative activity compared with naturally harvested seaweed. Metabolite profiling identified 47 compounds exhibiting differential accumulation patterns, with the natural specimens enriched in omega-3 polyunsaturated fatty acids, including docosahexaenoic acid, and the laboratory-acclimatized specimens exhibited elevated arachidonic acid levels. Amino acid profiling revealed higher concentrations of essential and non-essential amino acids in the natural specimens, with prominent levels of phenylalanine and aspartic acid, while the lab-acclimatized specimens were enriched in isoleucine, methionine, proline, and cysteine. The lab-acclimatized specimens exhibited significantly enhanced water absorption (WSC: 6 ± 0.25 mL/g DW; WHC: 2.68 ± 0.11 g/g DW) and higher total sugar (47.11 ± 0.52% Glc eq. DW) and phenolic contents (51.28 ± 0.54 mg GAE g⁻¹ extract), while the natural specimens had a superior oil-holding capacity (OHC: 1.8 ± 0.12 g/g DW); higher total flavonoid (123.62 ± 2.97 mg Q g⁻¹ extract), protein (5.11 ± 0.36 µg BSA eq/mg DW), and chlorophyll contents (8.82 ± 0.58 mg/L); and higher antioxidant activities (ABTS-EC₅₀: 67.33 ± 0.97 μg/mL extract). The mineral analysis revealed distinct elemental profiles, with enrichment of sodium, magnesium, and calcium in the lab-acclimatized specimens and a more favorable Na/K ratio (0.14 vs. 0.78) in the natural specimens. Of note, extracts from both seaweeds exhibited significant dose-dependent antiproliferative activity against HeLa cervical cancer cells (Wild EC₅₀: 118.63 ± 14.14 µg/mL extract; lab EC₅₀: 153.35 ± 10.18 µg/mL extract), suppressed colony formation in soft agar assays, induced nuclear condensation (based on Hoechst staining), and modulated the expression of key oncogenes (upregulating NDRG1, TP53, and CASP3 and downregulating BCL2, MYC, and CCND1). Collectively, this study provides an approach to acclimatize A. orientalis that may be utilized for developing a cultivation method. Moreover, this green seaweed has a great potential to be used for nutraceutical and functional food applications. Full article

Phytate (myo-inositol hexakisphosphate) is a polyphosphate found in plant-based foods whose intestinal absorption mechanisms are insufficiently understood. Due to its high affinity for calcium, phytate can deplete extracellular calcium and potentially affect tight junction integrity, which could increase paracellular permeability. This study investigated the permeation of phytate across Caco-2 cell monolayers depending on calcium concentration. Differentiated Caco-2 cells were cultured on semi-permeable membranes and incubated with various phytate concentrations (0.17–1.66 mM) in media with low (2.1 µM) or normal (1.8 mM) calcium concentration. Phytate permeability and tight junction integrity were analyzed using HPLC and Lucifer yellow as a paracellular marker. At low calcium concentration, significant permeability was observed starting from 0.55 mM phytate (~60% at 1.66 mM), while at normal calcium concentration, significant permeability was only detectable at 1.66 mM. The increased Lucifer yellow permeation correlated with phytate permeation and confirmed tight junction disruption. Phytate that reached the basolateral side at physiological calcium concentration precipitated completely as insoluble calcium–phytate complex. These results demonstrate that phytate can pass intestinal epithelium via the paracellular pathway and increase the paracellular permeability, especially at low apical concentrations of calcium. Full article

HIV latency, driven by a complex interplay of host factors, remains a key barrier to viral clearance. Current latency-reversing agents (LRAs) demonstrate limited efficacy and specificity, and none have been approved for clinical use. Although natural products have shown promise as LRAs, the therapeutic potential of fungal metabolites remains underexplored. Candida albicans, a prevalent human commensal and opportunistic pathogen, produces diverse secondary metabolites that can influence host pathways, affecting latency dynamics. This study aimed to investigate the latency-modulating potential of secondary metabolites of C. albicans using an integrative network pharmacology and computational pipeline. C. albicans secondary metabolites were retrieved from the literature, screened for drug-likeness, and mapped to human targets and biological pathways annotated in HIV latency. Key metabolites, hub genes, and pathways were systematically characterized through network and computational analyses. Six drug-like candidates, identified from 185 absorption, distribution, metabolism, excretion, and toxicity (ADMET)-screened metabolites, collectively mapped to 369 human genes with a 6.5% overlap in HIV latency (176 shared and 20 hub genes). These overlapping genes were significantly enriched for signal transduction, membrane localization, and adaptive responses to chemical stimuli. Kyoto encyclopedia of genes and genomes (KEGG) enrichment revealed oncogenic diseases (non-small cell lung, pancreatic, and prostate cancers) and latency-associated cascades, including PD-L1/PD-1, HIF-1, Ras, PI3K-Akt, calcium, and cAMP signaling. Six hub targets (MAPK1, PIK3CA, MAPK3, EGFR, MTOR, and AKT1) were consistently annotated within the top 30 KEGG pathways and displayed strong binding affinities for MET 15 and MET 119. Molecular dynamics (MD) simulations confirmed favorable binding free energies (BFEs) and stable conformational dynamics for the top-ranked metabolite MET 15. C. albicans secondary metabolites preferentially target oncogenic signaling networks central to HIV latency maintenance, notably PI3K/AKT/MTOR and MAPK/ERK, which regulate cell survival, metabolic homeostasis, and viral transcriptional repression. MET 15 is a top-ranked candidate metabolite for HIV latency-reversing therapeutics and warrants experimental validation in established latency models. Full article

The development of efficient, stable, and sustainably fabricated photocatalysts for solar-driven hydrogen evolution remains a critical challenge in the field. Herein, we report a novel green coprecipitation strategy to synthesize calcium-doped zinc oxide (Ca-ZnO) nanosheets, utilizing cactus juice as a natural, multifunctional medium for the coprecipitation process. This method enables the in situ, tunable incorporation of 3–7% Ca²⁺ ions into the wurtzite ZnO lattice without the use of harsh chemical reagents. Comprehensive characterization confirms that Ca²⁺ substitutionally replaces Zn²⁺, which preserves the intrinsic crystal structure of ZnO well while inducing the formation of uniform nanosheet morphology. This doping strategy effectively modulates the electronic band structure, progressively narrowing the bandgap from 3.19 eV to 2.90 eV and significantly enhancing visible-light absorption. Crucially, the incorporation of Ca²⁺ also generates oxygen vacancies, which serve as efficient electron traps to suppress photogenerated charge carrier recombination. The optimized 5%Ca-ZnO photocatalyst demonstrates a favorable hydrogen evolution rate of 889 μmol·g⁻¹·h⁻¹ under full-spectrum irradiation, with stability, retaining 94.8% of its activity after four cycles. This work not only provides a high-performance material but also establishes a generalizable, sustainable paradigm for the design of advanced semiconductor photocatalysts. Full article

Beach sands may harbor human pathogens and antibiotic resistance genes, prompting the proposal of low-dose quicklime (CaO; 1–3% w/w) as a remediation strategy to improve microbiological quality in highly contaminated areas. After application, CaO is converted into calcium carbonate (CaCO₃), yet the ecological effects of this residual compound on benthic fauna remain poorly understood. This study evaluated the short-term impact of CaCO₃-enriched sediment (3% w/w) on the Manila clam, Ruditapes philippinarum, under controlled mesocosm conditions. Adult clams were exposed for one week, and survival, burrowing behavior, feeding- and metabolism-related parameters (clearance, ingestion, absorption efficiency and rate, ammonia excretion), and oxidative stress (malondialdehyde, MDA) were assessed using a hierarchical design, with a tank as the experimental unit. No significant differences were detected between control and CaCO₃-enriched treatments for any measured endpoint. Survival remained high, functional responses showed overlapping ranges, and MDA levels did not differ significantly between groups. Although limited to short-term exposure and a single concentration, these findings suggest that residual CaCO₃ derived from quicklime application did not induce detectable adverse effects in adult R. philippinarum under the tested conditions. Further long-term and multi-species studies are needed to confirm ecological safety. Full article

Background: Obesity is commonly seen as a condition of overnutrition; however, it is paradoxically associated with micronutrient deficiencies. These deficiencies are clinically relevant and may contribute to the progression of obesity-related comorbidities through interconnected pathways, including chronic low-grade inflammation, oxidative stress, gut dysbiosis, and impaired nutrient absorption. Objectives: This narrative review aims to summarize current evidence regarding the prevalence, underlying mechanisms, and clinical consequences of micronutrient deficiencies in individuals with obesity, with particular emphasis on their metabolic implications and potential therapeutic strategies. Results: Among individuals with obesity, iron, zinc, magnesium, calcium, vitamin D, vitamin B12, and folate are the most frequently reported deficiencies. These deficiencies arise from multiple mechanisms, including poor diet quality, increased metabolic demands, and compromised gastrointestinal absorption. In addition, obesity-related alterations in pharmacokinetics may further interfere with micronutrient distribution and bioavailability. Together, these mechanisms may lead to various clinical outcomes, such as anemia, immune, metabolic, and cardiovascular dysfunctions, along with cognitive impairment. Although several studies suggest that correcting these deficiencies may improve clinical outcomes, findings remain inconsistent, highlighting the complex and multifactorial pathophysiology underlying micronutrient imbalance in obesity. Conclusions: Micronutrient deficiencies represent frequently overlooked contributors to metabolic dysregulation in obesity. Their identification and correction should be considered a central part of the obesity management strategy. A personalized supplementation approach, based on clinical, biological, and pathophysiological characteristics, may provide a complementary support for weight-management treatments. Full article

This study examines the carbonation behavior and CO₂ storage potential of a Ca-rich alkali-activated binder produced entirely from industrial residues-ladle furnace slag (LFS), coal ash (CA), and cement kiln dust (CKD). The system was designed as a one-part alkali-activated material (AAM), with CKD acting as an internal activator, and subjected to ambient curing, water curing, and accelerated CO₂ curing at ambient pressure. Phase evolution, microstructural development, and pore-structure characteristics were investigated using X-ray diffraction, FTIR spectroscopy, DSC–TG analysis, scanning electron microscopy, and X-ray micro-computed tomography, together with measurements of density, water absorption, and compressive strength. Loss-on-ignition measurements combined with chemical analysis were further used to quantify CO₂ uptake and evaluate the degree of carbonation of the binder system. CO₂ curing fundamentally altered the reaction pathway of the binder, shifting it from hydration-dominated to carbonation-controlled phase evolution, leading to the decomposition of calcium-bearing hydrates and complete carbonation of non-hydraulic γ-belite with the formation of vaterite, aragonite, and calcite. These transformations induced pronounced microstructural densification, reflected in a near-doubling of compressive strength (>48 MPa), increased apparent density, reduced water absorption, and simplified pore-network topology. A preliminary carbon footprint assessment indicates that the production of 1 m³ of the developed LFS–CA–CKD concrete generates about 14.36 kg CO₂-eq, while the carbonation process enables significant CO₂ sequestration, resulting in a net negative carbon balance. The results demonstrate that controlled carbonation is an effective post-treatment strategy for waste-derived alkali-activated binders, enabling simultaneous performance enhancement and permanent CO₂ sequestration. Full article

Bacteria-based self-healing concrete is extensively shown to improve strength and durability; yet, the mechanistic relationship among microbial activity, damage progression, and transport resistance is still ambiguous. This study examines the interrelated mechanical and transport properties of concrete that incorporates Bacillus subtilis by directly substituting mixing water. Concrete mixtures with 0%, 5%, and 10% bacterial solution were assessed for compressive strength, complete stress–strain response, split tensile strength, flexural toughness, fast chloride ion penetration, and capillary sorptivity. X-ray diffraction was employed for microstructural validation. Results indicate a dose-dependent shift from brittle to quasi-ductile behavior, marked by augmented strain capacity, postponed crack localization, and improved post-cracking energy absorption. The mechanical alterations resulted in substantial decreases in chloride ion penetrability (up to 57%) and capillary sorptivity (up to 60%), signifying a drop in crack-assisted transport. X-ray diffraction verified the production of calcite resulting from microbial-induced calcium carbonate precipitation. The results indicate that the improvement in durability of bacterial concrete is attributable not only to pore filling but also to altered damage mechanisms that diminish the connectedness of transport channels, underscoring the potential of Bacillus subtilis as a bio-admixture for resilient structural concrete. Full article

Currently, one of the major trends in the construction industry is the creation of structures with increased strength and durability. The solution is the use of nanomaterials as modifiers for cementitious composites. The aim of this study is to produce concretes with a variable structure modified with a combination of aluminum oxide (NA) and titanium oxide (NT) nanoparticles with improved properties. A variatropic structure is characterized by differences in properties across the cross-section of the material. Concretes were produced using vibration (V), centrifugation (C), and vibrocentrifugation (VC) technologies. Modification was carried out with NA particles from 0% to 4.0% in increments of 1.0% and NT from 0% to 2.0% in increments of 0.5% of the binder mass. Through experimental study, the impact of combined nanomodification on the compressive strength, water absorption, and frost resistance of concrete created with different technologies was investigated. The most effective modification dosages with NA and NT particles were determined to be 2% and 1%. The determination of concrete properties and the statistical processing of experimental results were carried out in accordance with the requirements of standardized methods. Compared to control samples, the maximum compressive strengths for V, C, and VC concretes were 12.4%, 17.5%, and 20.3% higher, reaching 48.9 MPa, 58.4 MPa, and 62.9 MPa, respectively. The lowest water absorptions for V, C, and VC concretes were 5.21%, 4.24%, and 3.76%, which are 18.5%, 24.4%, and 29.2% lower than those of the control samples. After a series of freeze–thaw cycles—6 for V, 8 for C, and 10 for VC—the losses in compressive strength and mass of the nanomodified composites were less than those of the control samples, indicating an increase in the frost resistance of concrete. The influence of concrete production technology on the effect of nanomodification with NA and NT particles was proven. Nanomodified C and VC concretes have improved physical and mechanical properties compared to V concretes. Nanomodified concretes with a variable structure have a more organized microstructure with a greater number of clusters of calcium silicate hydroxides. The resulting variable-structure concrete has improved properties and can be used to manufacture columns, piles, and transmission line supports. Full article

Tea offers health benefits, but some teas accumulate high fluoride (F), posing fluorosis risks. However, the roles of individual tea components in regulating F bioavailability remain unclear. This study investigated the effects of major tea constituents on F metabolism in male rats (n = 5/group) administered F (40 mg/L) alone or with graded doses of epigallocatechin gallate (EGCG, 150–450 mg/kg); theaflavins, thearubigins, and theabrownin (TFs, TRs, TB, 200–800 mg/kg each); tea polysaccharides (TPSs, 25–250 mg/kg); and calcium and aluminum (Ca, Al, 800–3200 µg/kg each) via gavage. Pharmacokinetic analysis of plasma F (0–480 min) and fecal F excretion were assessed. The result showed that high-dose EGCG (450 mg/kg) reduced C_max by 61.76% and total exposure (AUC_0–t) by 37.48% compared to the control, while significantly increasing fecal F by 26.79% (p < 0.05). TB (800 mg/kg) delayed F absorption by prolonging T_max from 18 to 30 min and reduced C_max by 35.38% (p < 0.05). TPS (250 mg/kg) decreased C_max by 51.72% and AUC_0–t by 24.38% (p < 0.05). Ca and Al (800–3200 µg/kg) reduced C_max by 39.19–69.62%, and low-dose aluminum (800 µg/kg) increased fecal F by 35.58% (p < 0.05). These findings elucidate distinct roles of tea constituents in mitigating F bioavailability, providing a scientific basis for tea safety assessment and dietary interventions against F overexposure. Full article

There has been much development of composites of calcium phosphate and polymers for use as artificial bone, with other applications still ongoing, and clarification of the in vivo absorption mechanism is considered an important perspective. In order to clarify the absorption mechanism of bioabsorbable materials used for artificial bones and bone grafts, we prepared composites of calcium phosphate and polymers and conducted in vivo experiments in experimental animals using composites as implantation samples. Two typical types of calcium phosphate, β-tricalcium phosphate (β-TCP) and unsintered hydroxyapatite (uHA), were used as calcium phosphate, and copolymers of poly-dl-lactide-co-glycolide (PDLGA) and poly-l-lactide-co-glycolide (PLGA) were used as polymers. For samples composed of PDLGA and calcium phosphates, the weight ratios of calcium phosphate were set at 40% and 10% for uHA and 40% for β-TCP (uHA(40), uHA(10) and β-TCP(40), respectively). A composite sample of PLGA and uHA was also prepared with a weight ratio of 10% uHA (uHA(10)/PLGA), intending slow degradation of the polymer matrix compared to PDLGA. The samples were implanted in the metaphysis and diaphysis region of rabbits’ femur for up to 48 weeks. In this study, positron emission tomography/X-ray computed tomography (PET/CT) was used to continuously evaluate the changes in the samples and the accumulation of cells in the animals, and histological evaluation was performed, focusing on the time of characteristic changes in the PET/CT to confirm the cell types. The results are summarized as follows: (1) the absorption mechanism of the materials used in this study was suggested to be mainly phagocytosis by macrophages; (2) the disappearance rate was faster for β-TCP(40) compared with uHA(40); and (3) uHA(10), having a lower proportion of uHA, is not prone to aggregation and exhibited a similar disappearance result to β-TCP(40). These results suggest that phagocytosis by macrophages is the dominant path in resorption of the bioresorbable materials, and the resorption period varies depending on the type of polymer. It is important to optimize the type and amount of polymers and calcium phosphate in order to achieve a degradation rate of bioresorbable materials that corresponds to the extent of damage in the healing area. Full article