Search Results (3,734)

Osteoporosis is a major skeletal disorder. Increasing evidence suggests that gut microbiota-derived mechanisms may contribute to bone remodeling. The biological rationale for a gut–bone axis is well supported, but the clinical relevance of microbiome-targeted interventions remains uncertain. In this narrative review, we focus on prebiotics, probiotics, synbiotics, and postbiotics. We searched in the literature the progress from mechanistic observations to measurable skeletal outcomes in humans. We searched PubMed, Scopus, and Web of Science for literature published mainly between 2021 and 2026. We also included earlier studies when they were important for the mechanistic framework. The evidence was evaluated according to intervention type and outcome. We focused on bone turnover markers, bone mineral density, and the duration of exposure required for these outcomes to become clinically meaningful. Recent randomized trials and meta-analyses were also compared in a semi-quantitative synthesis to show where findings are consistent and where they remain conflicting. Full article

Organic-rich shale contains chemically heterogeneous mineral–organic interfaces that produce strong and spatially variable proton surface relaxation, complicating the identification of clay-bound water and the conversion of NMR relaxation time into pore size. Conventional interpretations commonly treat surface relaxivity as a constant, while the respective contributions of water-retaining surface chemistry, molecular restriction, and paramagnetic centers remain insufficiently separated. In this study, Wufeng–Longmaxi shale samples from the Yongchuan Block were investigated using mineralogical and pore structural characterization, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, cation exchange capacity, zeta potential, electron paramagnetic resonance, controlled hydration, one- and two-dimensional low-field time domain NMR, and molecular dynamics simulations. Under the present fluid and acquisition conditions, strongly surface-associated water was operationally identified mainly at T₂ < 1.6 ms and T₁ < 85 ms, while the effective transverse surface relaxivity ranged from 3.6 to 9.1 μm/s. Water retention was more closely associated with cation exchange capacity and surface –OH/O–C environments, whereas relaxation efficiency was controlled more directly by EPR-detectable paramagnetic centers and restricted molecular motion of interfacial water. Simulations of Na-smectite, chlorite, illite, and kerogen-covered illite revealed systematic differences in water density layering, adsorption strength, hydrogen bond persistence, molecular residence, translational diffusion, rotational reorientation, and proton–proton dipolar correlation. A chemistry-informed model combining the EPR-derived paramagnetic center density with a surface area-weighted molecular restriction index explained 86% of the measured relaxivity variation, with an adjusted R² of 0.83 and leave-one-out cross-validation RMSE and MAE values of 0.71 and 0.57 μm/s, respectively. At the core scale, the variable relaxivity interpretation reduced the mean absolute percentage error of characteristic pore diameter from 21.9% to 4.5% and the RMSE of the clay-bound water fraction from 3.4 to 0.4 percentage points relative to the fixed relaxivity method. Transfer to NMR logging further reduced lithology-dependent biases in pore size conversion and clay-bound water partitioning. These results define shale surface relaxivity as an emergent interfacial property arising from coupled magnetic and molecular controls and provide a mechanistic basis for NMR analysis of chemically heterogeneous shale materials. Full article

Peloids are thermotherapeutic agents used in several spas and thermal centers; their behavior depends on their physical properties, and these determine their forms of application. This work focuses on the study of the thermophysical properties of the mixtures of a clay, Laias mineral-medicinal water, and microalgae. The properties studied are density, specific heat, thermal conductivity, thermal diffusivity, and apparent viscosity as a function of the concentration of the water, at atmospheric pressure and a temperature of 308.15 K. The density of the mixtures was determined by a pycnometric method. The specific heat was determined using a CALVET microcalorimeter. A Decagon KD2 Pro conductivity meter was used to measure thermal conductivity. Thermal diffusivity was calculated from the data obtained on thermal conductivity, density and specific heat. Apparent viscosity measurements were carried out using a Schott rotational viscometer (Cole-Parmer, Vernon Hills, IL, USA). Results showed that the ternary mixtures with the highest percentage of mineral-medicinal water present the best thermotherapeutic behavior (95% water; Density: 1005 Kg/m³; Specific heat: 4037 J/kg K; Thermal conductivity: 0.592 W/m K; Thermal diffusivity: 0.146 × 10⁻⁶ m²/s; Apparent viscosity: 0.002 Pa s). The objective of this research is to contribute new knowledge in relation to microalgal peloid characteristics and their quality criteria concerned with therapeutic and wellness purposes, and how this could help in choosing the most suitable type of application for each mixture. Full article

Osteoporosis is one of the most prevalent metabolic bone diseases worldwide, and current pharmacological options are limited by adverse effects and are poorly suited to long-term use, underscoring the need for novel therapeutic targets. Bifidobacterium, one of the most representative beneficial bacterial genera in the human gut, has been linked to bone mineral density, and supplementation with specific strains improves bone metabolic parameters in animal models of osteoporosis. This narrative review examines the molecular mechanisms through which Bifidobacterium may protect bone via the gut–bone axis, encompassing four interconnected dimensions: reinforcement of the intestinal barrier, modulation of the immune network, remodeling of the gut microbiota, and production of bone-protective metabolites. The review makes three principal contributions. First, it establishes a four-tier mechanistic framework of Bifidobacterium-mediated regulation of osteoporosis in which the evidence is stratified into three categories—direct evidence from Bifidobacterium-specific studies, indirect evidence from other probiotics, and general mechanisms of gut microbiota-regulated bone metabolism—thereby strengthening the rigor of each argument and explicitly distinguishing evidence derived from Bifidobacterium-specific studies from that based on other probiotics or general gut-microbiota mechanisms throughout the review. Second, it systematically compares the osteoprotective efficacy of different Bifidobacterium strains (Bifidobacterium longum, Bifidobacterium lactis, Bifidobacterium adolescentis, etc.), highlighting the central importance of strain specificity. Third, it evaluates the strength of the evidence and identifies knowledge gaps for each mechanistic pathway. Most current evidence derives from cross-sectional studies and animal models; causal relationships await validation in large-scale prospective cohort studies and randomized controlled trials. In addition, functional disparities among strains and heterogeneity across clinical studies remain the core bottleneck in translating these fundamental findings into clinical practice. Full article

Background/Objectives: A dual-layer flat-panel detector (DFD), in which two flat-panel detectors are stacked vertically, enables single-shot dual-energy imaging without a fan-beam scanning and switching mechanism in conventional dual-energy X-ray absorptiometry (DXA), the clinical standard for bone mineral density (BMD). However, because single-shot BMD measurement systems using DFDs show substantial spectral overlap, their BMD measurement performance is inherently inferior to that of dual-shot systems. In this paper, we optimize the tube voltage, metal filter thickness, and CsI(Tl)-scintillator thickness so that the BMD estimation error of the single-shot method is similar to that of the double-shot method. Here, we also optimize the dual-shot approach to serve as a meaningful reference in the comparison. Methods: BMD measurement simulations were performed using a polynomial estimator based on second-order polynomial fitting of dual-energy logarithmic intensities. Performance comparison was based on noise sensitivity, quantified by the condition number and mean square error under a multiplicative noise model, and was further assessed using the equivalent energies and the bone-tissue attenuation ratios. Results: The simulation results indicate that, in the dual-shot approach, decreasing the low tube voltage is the most effective strategy for improving BMD measurement performance, whereas in the single-shot approach, reducing the upper scintillator thickness has the largest impact. Conclusions: When both approaches are evaluated under their respective optimized configurations based on synthetic simulations, the single-shot approach demonstrates that the BMD estimation error is sufficiently similar to that of the dual-shot approach, supporting its potential as a hardware-efficient alternative for BMD measurement. Full article

The article presents the results of a study on the growth, development, response to mineral nutrition and yield stability of 16 varieties of spring barley on chernozem soils of Northern Kazakhstan, cultivated under three backgrounds of mineral nutrition—without fertilizers, half of the calculated dose (N₃₀P₃₅) and the full calculated dose (N₆₀P₇₀) of fertilizers. The reserves of productive moisture, the content of nitrate nitrogen, mobile phosphorus, exchangeable potassium, pH of the water extract in the soil, phenological development of plants, plant density, elements of crop structure, yield, ecological plasticity to mineral nutrition and stability of yield of barley varieties were studied. It was found that the use of mineral fertilizers increased the average grain yield by 0.29–0.46 t/ha (24.0–38.0%) compared to the unfertilized background. The varieties Kudesnik (+0.77 t/ha; +98.7%), Prairie (+0.80 t/ha; +63.0%) and Arna (+0.64 t/ha; +66.0%) showed the greatest response to fertilizers; the maximum yield was achieved by the varieties KWS Salome (2.30 t/ha) and Vakula (2.28 t/ha) with the full calculated dose of fertilizers. Correlation analysis showed that, against an unfertilized background, yield was most closely related to the 1000-grain weight (r = 0.75), the number of plants before harvesting (r = 0.63), and the number of productive stems (r = 0.53), indicating the leading role of these traits in yield formation. The values of the ecological plasticity coefficient (bi) varied from 0.6 to 1.7, and the yield stability index (Hom) varied from 3.4 to 6.9, which reflects significant differences in the adaptive response of varieties to changes in the level of mineral nutrition. According to the type of adaptability, the following varieties were selected for extensive technology: Velikan, Slavny, Divny, Abalak, Kerzhak, for resource-saving: Astana 2000, Arna, Tselinny-60, Grace, Eifel and intensive technology: KWS Salome, Vakula, Prairie, Paustiana, Ara, Kudesnik, recommended for the corresponding cultivation technologies. Full article

Environmental contaminants (ECs) may impair skeletal health through endocrine disruption, oxidative stress, inflammation, and altered mineral homeostasis. This systematic review and meta-analysis evaluated the associations between EC exposure and osteoporosis-related outcomes in adults. PubMed/MEDLINE, Scopus, and Web of Science were searched in April 2026 for English-language studies published from 2016 onward. Study selection followed PRISMA guidelines, while methodological quality was evaluated using the Joanna Briggs Institute (JBI) checklist and Newcastle–Ottawa Scale (NOS). Evaluated contaminant classes encompassed ambient air pollution (PM2.5, PM10, PM1, NO₂, NO_x, SO₂, CO, O₃), per- and polyfluoroalkyl substances (PFAS), heavy metals and trace elements (e.g., cadmium, lead), pesticides, polycyclic aromatic hydrocarbons (PAHs), phthalates, volatile organic compounds (VOCs), persistent organic pollutants (POPs, dioxins, PCBs), brominated flame retardants (BFRs), and water disinfection by-products. Random-effects meta-analyses using restricted maximum likelihood estimation were conducted when at least 3 studies were available. Forty-eight studies involving 4,510,868 participants were included. Air contaminants showed the most consistent associations with reduced bone mineral density (BMD) and osteoporosis, followed by selected PFAS and cadmium exposures. Evidence for pesticides, PAHs, phthalates, volatile organic compounds VOCs, POPs, flame retardants, and water disinfection by-products was less consistent. PM2.5 exposure was associated with increased osteoporosis risk (OR = 1.24, 95% CI: 1.02–1.51), and to a lesser extend also PM10 (OR = 1.17, 95% CI: 0.96–1.42). The analyses showed extreme heterogeneity and sensitivity to influential studies. ECs, particularly fine particulate matter, may contribute to skeletal deterioration, although the findings require cautious interpretation. PROSPERO ID: CRD420261460078. Full article

This study aimed to evaluate bone regeneration in critical-size rat calvarial defects treated with a xenogeneic bone graft alone or combined with autologous platelet concentrates prepared using two distinct centrifugation protocols, one based on horizontal centrifugation to produce horizontal platelet-rich fibrin (H-PRF) and the other based on vertical fixed-angle centrifugation to produce leukocyte–platelet-rich fibrin (L-PRF). Calvarial defects were created in 24 rats and allocated to four groups: blood clot (C), xenograft (XEN), xenograft plus L-PRF (XEN+L-PRF), and xenograft plus H-PRF (XEN+H-PRF) (n = 6/group). Calcein and alizarin were administered at 14 and 30 days, respectively. After 35 days, specimens were analyzed by micro-computed tomography, confocal laser scanning microscopy, histomorphometry, and histopathology. Data were analyzed using ANOVA and Tukey’s post hoc test (p < 0.05). All treated groups showed higher bone volume and lower trabecular separation than group C. The XEN+L-PRF group showed significantly higher bone volume than the XEN group. The XEN+H-PRF group showed higher bone volume, connectivity density, alizarin labeling, mineral apposition rate, and newly formed bone area, as well as lower trabecular separation, than the other groups (p < 0.05). Under the experimental conditions evaluated, both PRF protocols improved bone regeneration when combined with a xenogeneic bone graft, whereas the H-PRF protocol was associated with superior structural and histomorphometric bone regeneration outcomes and with more favorable spatiotemporal mineralization kinetics. Full article

Tantalum and niobium are critical strategic rare refractory metals; however, most associated tantalum–niobium resources are characterized by ultra-low grade, finely disseminated grains, and severe argillization, which causes pronounced slime coating of gangue mica on valuable mineral surfaces and impedes efficient recovery via gravity separation. In this study, an innovative beneficiation route combining sodium silicate pre-dispersion conditioning with shaking-table gravity separation was proposed to recover a spodumene-dominant pegmatitic lithium ore containing trace associated Nb–Ta minerals, with mica as the major slime-forming gangue. Process mineralogy analysis revealed that the raw ore has a total (Nb,Ta)₂O₅ grade of only 0.019%, with the main valuable minerals being columbite-(Mn), columbite–tantalite, and tantalite, whereas layered mica minerals constitute the primary argillization gangue that readily generates micro-fine slimes smaller than 5 μm. Single-factor tests demonstrated that the optimal grinding fineness was 84.4% passing 200 mesh, and the optimal feed pulp density for gravity separation was 28.6%. Adjusting pulp concentration alone, without a dispersant, yielded a Nb₂O₅ concentrate grade of merely 0.144%, as severe slime coating greatly limited separation selectivity. Following the introduction of sodium silicate for pre-dispersion, the separation performance improved markedly at the optimal dosage of 300 g/t: the concentrate Nb₂O₅ grade reached 1.28% (8-fold higher than the blank test), and the Ta₂O₅ grade increased to 0.47% (85-fold higher than the blank test). Multi-scale characterization, including zeta potential measurements, ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), was employed to elucidate the dispersion mechanism of sodium silicate. The results confirmed that sodium silicate undergoes selective chemisorption on mica surfaces by forming Si–O–Al bonds with surface Al–OH active sites, which substantially increases electrostatic repulsion between mineral particles and eliminates mica slime coating on tantalum–niobium minerals. In contrast, sodium silicate exhibits only weak physical adsorption on tantalum–niobium mineral surfaces, with no evident chemical bonding. This work provides a low-cost, eco-friendly pretreatment–gravity separation coupling technology for the efficient enrichment of argillized ultra-low-grade tantalum–niobium associated ores and offers theoretical guidance for the green utilization of complex tantalum–niobium tailings and low-grade mineral resources. Full article

Osteoporosis requires long-term management, yet current pharmacological therapies are limited by safety concerns. Calcium carbonate is a biocompatible and widely used calcium supplement; however, its low absorption efficiency restricts therapeutic effectiveness. Herein, a biomimetic calcium delivery system was constructed by depositing an ultrathin (~10 nm) tannic acid/fish collagen (TA/FC) nanolayer onto CaCO₃ nanoparticles via coordination- and hydrogen bonding-mediated self-assembly. The TA/FC nanocoating modulates cellular internalization by activating multiple endocytic pathways, thereby enhancing nanoparticle uptake and intracellular calcium delivery. As a result, cellular calcium uptake increased by 5.6-fold, and the apparent absorption rate reached 93.2%, 4.9 times higher than that of medical-grade calcium carbonate. In vivo, CaCO₃@TA/FC nanoparticles restored bone metabolic homeostasis, as indicated by increased serum calcium, decreased phosphate and alkaline phosphatase levels, and elevated osteoprotegerin expression. This was accompanied by significant improvements in bone microarchitecture, including increased bone mineral density, bone volume fraction, trabecular number and thickness, as well as recovery of mechanical strength. Overall, this work demonstrates that interfacial engineering enhances calcium bioavailability and improves the therapeutic performance of calcium carbonate. Full article

Biomass-derived carbons hold substantial promise for sustainable electrochemical energy storage due to their low cost, wide availability, and intrinsic heteroatom- and mineral-rich nature. However, the fundamental influence of carbonization temperature on the structural evolution of non-activated biomass-derived carbons remains insufficiently understood. In this work, corn straw-derived carbon (CS) is produced without any chemical additives to isolate the intrinsic effects of carbonization temperature on its physicochemical properties. Systematic temperature variation from 600 to 1000 °C reveals pronounced changes in micro-morphology, pore development, defect density, and the ordering of the carbon matrix, all strongly governed by the inherent mineral content of corn straw. Electrochemical evaluation in alkaline electrolyte demonstrates that CS-800 delivers the highest specific capacitance of 53.8 F g⁻¹ at 1 A g⁻¹ in a three-electrode configuration and maintains favorable rate capability in a symmetric supercapacitor device. The symmetric coin-cell supercapacitor device assembled with CS-800 as the electrodes achieved an energy density of 3.64/5.8 Wh kg⁻¹ and a power density of 5200/750 W kg⁻¹, along with remarkable cycling stability over 30,000 cycles with negligible capacitance loss. Overall, this study provides mechanistic insight into temperature-driven structural evolution in non-activated biomass-derived carbons, offering a fundamental understanding that may guide the rational design and future development of sustainable carbon electrodes for electrochemical energy-storage applications. Full article

Background/Objectives: Modifiable lifestyle behaviors may be relevant to osteoporotic fracture risk, but their cumulative association across different levels of skeletal health remains unclear. This study investigated the association between a cumulative lifestyle score and osteoporotic fracture risk according to baseline bone mineral density (BMD) category in older women. Methods: We conducted a nationwide retrospective cohort study using Korean National Health Insurance Service data from 541,770 women aged 66 years who underwent dual-energy X-ray absorptiometry through the national life-transition health screening program between 2010 and 2016. A cumulative lifestyle score ranging from 0 to 3 was constructed by assigning one point each for regular exercise, non- or ex-smoking status, and non-drinking status. Cox proportional hazards models were used to evaluate associations with any, vertebral, hip, and other osteoporotic fractures across normal BMD, osteopenia, and osteoporosis groups. Results: Higher lifestyle scores were generally associated with lower osteoporotic fracture hazards across BMD categories. For any fracture, the adjusted hazard ratios for lifestyle score 3 versus 0 were 0.746 (95% CI, 0.564–0.987) in the normal BMD group, 0.747 (95% CI, 0.630–0.885) in the osteopenia group, and 0.786 (95% CI, 0.668–0.924) in the osteoporosis group. No statistical evidence of interaction between lifestyle score and BMD category was observed. The incidence-rate differences between scores 0 and 3 for any fracture were 4.49, 6.03, and 5.99 per 1000 person-years in the normal BMD, osteopenia, and osteoporosis groups, respectively. Conclusions: A more favorable cumulative lifestyle profile was associated with lower osteoporotic fracture risk across BMD categories in older women. Although there was no statistical evidence that the relative associations differed by BMD category, larger incidence-rate differences were observed among women with lower BMD. These observational findings support the potential value of integrated lifestyle assessment as a complementary component of fracture-risk assessment and counseling. Full article

To compare resistance to apple Valsa canker across scion–rootstock combinations and to identify key evaluation indicators and superior resistant combinations, we established 15 scion–rootstock pairings using ‘Yueyanghong’, ‘Harlikar’, and ‘Qiufuhong’ as scions and Qingzhen No.1, Qingzhen No.2, M. baccata Borkh., M. robusta Rehd., and M. hupehensis Rehd. as rootstocks. We assessed resistance under natural field infection conditions. We measured plant growth indices, leaf photosynthetic parameters, anatomy of one-year-old shoots, and mineral nutrient contents for each combination. We then performed correlation analysis with the disease index to identify relationships between these indicators and disease occurrence under diseased conditions and to clarify their physiological basis. Finally, we comprehensively evaluated grafting compatibility and disease resistance among scion–rootstock combinations to identify combinations that might reduce Valsa canker severity and the associated predictive indicators. Results indicated that combinations using ‘Yueyanghong’ as the scion had the lowest overall disease index. In particular, ‘Yueyanghong’/Qingzhen No.2 showed the best graft compatibility (FCC = 2.10, RSR = 1.10) and the most favorable comprehensive disease-resistance profile. ‘Yueyanghong’/M. hupehensis Rehds exhibited the highest photosynthetic rate. By contrast, ‘Harlikar’/Qingzhen No.2 and ‘Qiufuhong’/M. baccata Borkh displayed relatively high disease indices and were classified as highly susceptible under the experimental field conditions. Lower disease index correlated with higher leaf net photosynthetic rate and with higher intercellular CO₂ concentration. Combinations with low relative electrical conductivity retained greater membrane-system stability. A lower disease index was positively associated with higher potassium (K) content, while higher iron (Fe), manganese (Mn), and zinc (Zn) contents correlated with increased disease index. Finally, lower disease index corresponded to greater shoot phloem thickness and higher cell density. In conclusion, using the disease index as a quantitative measure and integrating multidimensional indicators, plant growth, photosynthetic physiology, mineral nutrition, and shoot anatomical structure, allows preliminary evaluation of compatibility and disease resistance across scion–rootstock combinations. Full article

Mediterranean ecosystems are particularly exposed to wildfire because seasonal summer drought, high temperatures, and flammable vegetation favour fire ignition and spread. Because post-fire nutrient patterns are context dependent, this observational study compared soil organic carbon (SOC) and nitrogen (N) stocks and selected physicochemical properties among sampling campaigns conducted before and after a wildfire in Vesuvius National Park (Italy). Surface mineral soil (0–10 cm) was sampled beneath two vegetation-cover categories (shrubs and trees) before fire (2015–2017) and approximately 22, 46, and 70 months after fire. Soils were analysed for pH, water content (WC), soil organic carbon concentration (Corg), total N concentration, bulk density, Corg:N ratio, and apparent fixed-depth soil organic carbon (SOC) and N stocks. Soil properties varied primarily among sampling periods, whereas vegetation category showed a more limited association. The short-term campaign was characterised by the highest pH and the lowest WC and total N concentration, whereas total N concentration and apparent fixed-depth N stock reached the highest median values during the long-term campaign. Vegetation category was associated only with WC and Corg:N ratio, which were generally higher under trees, and no significant sampling period × vegetation interaction was detected. Corg concentration and apparent fixed-depth SOC stock did not differ significantly among sampling periods. These differences cannot be attributed exclusively to wildfire or elapsed time because contemporaneous unburnt controls were unavailable and sampling period, calendar year, and spatial variability were not fully separable. The findings nevertheless show the value of jointly monitoring element concentrations and soil physical properties when assessing Mediterranean forest soils after wildfire. Full article

Countermovement jump (CMJ) assessment is widely used to evaluate lower-body neuromuscular performance, but its potential relationship with bone health remains insufficiently understood. This study aimed to determine whether eccentric-phase force–time characteristics during the CMJ are associated with proximal femur bone density, mass, and structural properties in postmenopausal women. One hundred and ten physically inactive women within 10 years after menopause underwent bone and jump assessments. Areal bone mineral density and bone mineral content were measured using dual-energy X-ray absorptiometry, and three-dimensional cortical and trabecular proximal femur parameters were estimated from dual-energy X-ray absorptiometry images. Participants performed maximal countermovement jumps on a force platform. Seventeen eccentric-phase force–time variables were extracted and reduced using principal component analysis. Multivariable linear regression models adjusted for age, body mass, height, waist circumference, and hip circumference examined associations between eccentric mechanical profiles and bone outcomes. Four principal components explained 90.5% of the variance in eccentric jump mechanics. Regression models explained between 11% and 41% of the variance across bone outcomes, with the strongest models observed for trabecular bone mineral content at the femoral neck (R² = 0.41), bone mineral content at the femoral shaft (R² = 0.40), and total trabecular volume (R² = 0.39). The component reflecting greater countermovement depth and longer eccentric duration showed the most consistent contribution across models, whereas the force–power component contributed to selected trabecular outcomes. These findings suggest that the combined eccentric mechanical profile of the CMJ is associated with proximal femur bone properties in physically inactive women in early postmenopause and may help inform the biomechanical assessment of bone health and the development of bone-targeted exercise interventions in this population. Full article