Search Results (78)

Elevated reactive nitrogen (N) inputs from fertilization and fossil fuel combustion increasingly threaten the soil carbon storage capacity of grassland ecosystems. However, the stability of soil organic carbon within these ecosystems is increasingly at risk. Recent research has highlighted the importance of microbial residues in regulating the stability of soil organic carbon. Despite this recognition, there is still a limited understanding of the impact of microbial residues on soil organic carbon stability in grasslands subjected to external nitrogen inputs, as well as the underlying regulatory mechanisms involved. This review aims to synthesize current knowledge on how nitrogen (N) addition and its duration regulate microbial residue accumulation and its contribution to SOC pools (particulate organic carbon (POC) and mineral-associated organic carbon (MAOC)) in grassland ecosystems, with emphasis on the roles of microbial community composition, microbial biomass carbon, and enzyme activities. By integrating these perspectives, this review aims to advance understanding of the mechanisms governing microbial residue dynamics under nitrogen enrichment and to identify priorities for future research. Full article

Clay mineral diagenesis occurs in all buried siliciclastic sediments, albeit fine-grained and low-permeable or coarse-grained and highly permeable. Because of the limited permeability after compaction, this sheds doubt on the presumption that fluid flow is a causal factor in burial diagenesis besides temperature and effective pressure conditions. To assess the influence of fluid flow on their diagenesis, a number of sandstones have been studied focusing on clay minerals. In the studied sandstones, the authigenic clay minerals show a considerable variation in their chemical composition and mineralogy. In particular, authigenic illite and chlorite are common as authigenic cements in sandstones, often forming grain-rimming cements. Each of these two authigenic clay minerals varies distinctly in chemical composition, mineralogy and crystal habit at a small scale, compared to individual pores and laminae/beds. This indicates that local conditions determined not only which authigenic clay minerals formed, but also their chemical composition. Local conditions include the detrital mineral assemblage, specific textural features including clay grain coatings, and the ratio of the volume of susceptible components to pores. During burial diagenesis, a number of elements involved in clay mineral authigenesis, including Al, K, Mg and Fe, are locally fixed by clay mineral precipitation. In addition, diagenesis is driven by the amount and distribution of susceptible detrital components and the changes in physical conditions including temperature and effective pressure. The physical conditions allow chemical processes to commence and continue. The evidence presented is inconsistent with external fluid flow as a causal agent of burial diagenesis, supporting a largely closed, diagenetic system. Full article

Poor classroom acoustic conditions can impair speech intelligibility, increase cognitive load, and reduce the quality of learning environments. Simulation-guided optimization provides a promising approach for improving building acoustic performance and indoor environmental quality while reducing trial-and-error material selection in renovation practice. The field-validated optimized configuration combined slotted wood sound-absorbing panels and mineral wool panels, with a total material cost of 1512 RMB. Field measurements showed that this configuration reduced RT from 2.42–1.76 s to 0.78–0.43 s. In addition, the simulation-based STI evaluation increased from 0.19 to 0.75, indicating a potential improvement in speech intelligibility. Since STI was not directly measured in the field, this result is interpreted as a model-based prediction supported by the calibrated RT validation. The average relative error between simulated and measured RT values was 6.83%, demonstrating the predictive reliability of the calibrated model for RT prediction. The proposed framework provides a practical decision-support method for cost-controlled acoustic renovation of educational buildings and was validated using an existing classroom case. The framework was demonstrated using one existing classroom and provides a methodological basis for adaptation to other educational spaces by updating room-specific inputs. Its external transferability requires validation in additional classrooms. Full article

Microbial functional traits play a central role in regulating carbon mineralization efficiency (CME) in peatlands, yet how they respond to concurrent warming and atmospheric nitrogen deposition remains unclear. In this study, peat soils from three vegetation types (sedge, reed, and shrub) were subjected to controlled microcosm incubations simulating warming and nitrogen addition gradients. Microbial community composition and functional profiles were characterized using 16S rRNA high-throughput sequencing and Functional Annotation of Prokaryotic Taxa (FAPROTAX) functional prediction, while dissolved organic matter (DOM) composition was analyzed via excitation–emission matrix fluorescence spectroscopy with parallel factor analysis (EEM-PARAFAC) and fluorescence indices. Integrating correlation analysis, Random Forest, and partial least squares path modeling (PLS-PM) modeling, we identified microbial functional traits as key factors linking environmental changes to soil CME, with DOM serving as a substrate-mediated pathway. External nitrogen input primarily drove shifts in microbial functional composition, whereas warming modulated substrate utilization preferences and DOM turnover. The interaction between warming and nitrogen selectively reshaped microbial functional profiles, thereby jointly determining CME. Functional traits explained more variation in CME than taxonomic composition, indicating a “structure–function decoupling” under environmental change. These findings highlight the central role of microbial functional traits in peatland carbon transformation and suggest that the net response of peatland carbon emissions to future environmental change will depend critically on the balance between warming magnitude and nitrogen deposition levels. Full article

C. c. rubrofuscus is an economically important species in South China. During breeding, some individuals develop skeletal softening, but the underlying mechanisms remain unclear. In this study, five-month-old C. c. rubrofuscus were classified into a hard-bone group and a softened-bone group based on X-ray radiography. A systematic comparison was then conducted between the two groups, including analyses of external morphology, skeletal morphology, vertebral bone mineral density (BMD), calcium (Ca) and phosphorus (P) levels in serum and bone tissue, bone histology, and the expression of autophagy-related genes and proteins. The prevalence of the softened-bone phenotype was approximately 14% in the cultured population. Compared with the hard-bone group, the softened-bone group showed significantly lower vertebral BMD, significantly increased serum Ca levels, significantly decreased serum P levels, and markedly reduced Ca and P contents in bone tissue. In addition, varying degrees of deformity were observed in the ribs, caudal intermuscular spines, and urostyle. Histological examination further revealed severe skeletal malformations in the softened-bone group, characterized by irregular cortical bone thickness in the ribs and pterygiophores, together with a significantly reduced osteocyte density. Meanwhile, microtubule-associated protein 1 light chain 3 (LC3) levels were significantly increased, whereas sequestosome 1 (p62) levels were significantly decreased. The upregulated expression of autophagy-related genes suggested dysregulated autophagy, which may contribute to osteocyte loss. Collectively, these results indicate that the softened-bone phenotype in C. c. rubrofuscus is not associated with obvious changes in external body morphology. However, disrupted Ca-P homeostasis, together with altered autophagy, may impair osteocyte viability and bone mineralization, ultimately leading to bone softening and skeletal deformity. These findings provide a theoretical basis for further investigation of the mechanisms underlying bone softening and deformity in C. c. rubrofuscus and for the genetic improvement and selective breeding of cyprinid fish to reduce the occurrence of the softened-bone trait. Full article

Rare earth elements (REEs) play a critical role in provenance tracing and the environmental reconstruction of the Earth. However, systematic investigations into the geochemical behavior and fractionation mechanisms of REEs during halite crystallization in brine–salt systems remain limited. This study reports new trace element and REE data for Late Cretaceous halites from the Thakhek Basin, Laos. Ratios of Sr/Ba, Sr/Cu, and V/Cr indicate a marine origin for the halites, which formed under hot climatic and oscillating oxidizing–anoxic redox conditions. Both primary and secondary halites display uniform Post-Archean Australian Shale (PAAS)-normalized REE distribution patterns, characterized by relative enrichment in medium rare earth elements (MREE) and depletion in light (LREE) and heavy rare earth elements (HREE). Similar REE patterns are also observed in halites from other modern and ancient, continental and marine salt basins worldwide. These observations suggest that the influences of parent brine composition and external provenance supplies on REE fractionation are negligible, given the consistent source, salinity, and redox conditions recorded in these halites. Accordingly, REE fractionation in halite was largely controlled by crystallographic effects, with aqueous MREE preferentially incorporated into halite crystals during deposition. In addition, the relatively lower Zr/Hf ratios in secondary halites compared to primary halites further validate the utility of the Zr/Hf ratio for distinguishing authigenic halite from salt modified by diagenesis, weathering, dissolution, or recrystallization. While our results establish a fundamental REE distribution pattern for halite, further research is needed to better constrain the underlying fractionation mechanisms of REEs in evaporite minerals within brine–salt systems. Full article

This study presents an integrated geological and environmental radiological analysis of basaltic volcanic rocks, which have been characterized by their suitability and potential for risk when used as construction materials. A total of thirty-five representative basaltic samples from the environment of studied area, located in the Northern Eastern Desert of Egypt, were utilized for this study. The rocks were then analyzed by means of HPGe high-resolution gamma-ray spectrometry methods. The petrographic studies show that the basalt samples were composed mostly of three main minerals: plagioclase, olivine, and pyroxene. In addition, these rocks have a significant degree of secondary alteration products, including sericite, epidote, and zoethite. For uranium-238 (²³⁸U), thorium-232 (²³²Th), and potassium-40 (⁴⁰K), the average activity concentration measured 53 ± 20 Bq kg⁻¹, 54 ± 14 Bq kg⁻¹, and 1178 ± 269 Bq kg⁻¹, respectively. Using the current global reference limits, all the measured values are above acceptable levels for the radionuclides ²³⁸U, ²³²Th, and ⁴⁰K. The radiological indices calculated for each of the basalt volcanic samples measured radium equivalent activity (Ra_eq = 221 Bq kg⁻¹), external hazard index (H_ex = 0.60), internal hazard index (H_in = 0.74), gamma index (Iγ = 0.84), and annual effective dose (AED = 0.52 mSv y⁻¹) indicate that the radiological hazard values of these samples are acceptable, unlike several samples, where values are near or exceed the accepted standards for indoor hazards. The most significant finding of this study reveals that the major contributions in the environment from radiological risk can be attributed to radionuclides ²³⁸U and ⁴⁰K based on correlation analysis, hierarchical clustering, and PCA analyses, and this study establishes the first multivariate perspective of how radiogenic materials controlled by the environment can affect basaltic rocks. Therefore, this study creates an important baseline for future environmental monitoring and states that caution is warranted when using basalt as a finished material for constructed environments, and for using basaltic products as raw materials in indoor environments. Full article

The Southwestern Fujian Region is one of the important Fe polymetallic metallogenic belts in China. The Makeng-Yangshan Fe skarn sub-belt within it contains several deposits that share a similar geological setting, mineralization age, and genetic type, yet exhibit significant differences in metal endowment. To investigate the poorly constrained factors responsible for these differences, this paper focused on the mineral chemistry of garnets associated with magnetite from the Makeng, Luoyang, and Yangshan Fe deposits within the sub-belt, employing in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for trace element analysis. Our results reveal that garnet from all three deposits are andradite-dominated and features a chondrite-normalized REE fractionation pattern exhibiting enrichment in LREE relative to HREE, indicating crystallization from unified, mildly acidic fluids under high oxygen fugacity (f_O2) conditions. However, both the Makeng and Luoyang garnets showed a strong positive Eu anomaly, whereas the Yangshan garnets displayed the weakest Eu anomaly among the three deposits, which can likely be attributed to the highest f_O2 environment of the Yangshan deposit. Furthermore, garnet Y/Ho ratios and Y-ΣREE correlations demonstrate that the Makeng and Luoyang garnets crystallized in an open fluid system that were primarily of magmatic-hydrothermal origin with substantial external fluid (e.g., meteoric water) involvement, whereas the Yangshan garnet reflects a relatively closed fluid system that was predominantly of magmatic-hydrothermal origin with limited external fluid input. These geochemical differences have direct implications for exploration: the open-system Makeng deposit holds promise for Mo-W-Sn mineralization, as does the Luoyang deposit for W-Sn, whereas the closed-system Yangshan shows little potential for these metals. In addition, this study reveals that Pb and Zn concentrations in garnet are not reliable exploration indicators. Overall, these findings provide important mineralogical constraints on the factors controlling deposit scale and metal associations, thereby enhancing the understanding of regional metallogeny and guiding future mineral exploration. Full article

The papermaking and recycling industries face increasing demands to improve efficiency, product quality, and environmental performance under conditions of water closure and high furnish variability. This study presents a comprehensive assessment of process control and management strategies for optimizing fines behavior, retention and fixation efficiency, de-inking performance, and ash balance in modern papermaking systems. The surface chemistry of fines was found to play a pivotal role in regulating charge distribution, additive demand, and drainage behavior, acting both as carriers and sinks for dissolved and colloidal substances. Results show that light, targeted refining enhances external fibrillation and produces beneficial fines that strengthen fiber bonding, while excessive refining generates detrimental fines and impairs drainage. Sequential retention programs involving polyamines, polyaluminum compounds, and microparticle systems significantly improve fines capture and drainage stability when operated under controlled pH and ionic strength. In recycling operations, optimized flotation conditions coupled with detackifiers and mineral additives such as talc effectively reduce micro-stickies formation and deposition risks. Ash management strategies based on partial purge and coordinated filler make-up maintain bonding, optical properties, and energy efficiency. Overall, the findings emphasize the need for an integrated wet-end management framework combining chemical, mechanical, and operational controls. Perspectives for future development include the application of biodegradable additives, nanocellulose-based reinforcements, and data-driven optimization tools to achieve sustainable, high-performance paper manufacturing. Full article

At present, phosphogypsum, as an industrial by-product, is a solid waste in phosphoric acid production, and its accumulation has caused serious environmental pollution. Furthermore, due to the insufficient insulation properties of traditional wall materials, the issue of a rising proportion of building energy consumption in total social energy consumption has become increasingly pressing. The study investigated vitrified beads as a light aggregate and phosphogypsum, mineral powder, and quicklime as an inorganic composite cementitious system to prepare the phosphogypsum-based lightweight thermal insulation material. The effect mechanism of the initial material ratio on the mechanical properties and micro-morphology of insulation materials was studied by macroscale mechanical property testing, X-ray diffraction, and scanning electron microscopy. Meanwhile, in order to meet the performance indexes specified in relevant standards, insulation materials were modified by adding sulfate aluminate cement, basalt fibers, and a waterproof agent to improve the strength, toughness, and water resistance. Based on the single-factor experimental design, the optimal dosage of various admixtures was obtained. The results indicated that the optimal properties of the sample were achieved when the binder–bead ratio was 1:4, the water–binder ratio was 1.6, the dosage of hydroxypropyl methylcellulose was 0.1%, and the solid content of waterborne acrylic emulsion was 24%. The optimal dosages of cement and fibers were 8% and 0.9%, respectively. The cement hydration products and gypsum crystals lapped through each other, filling the pores in the matrix and increasing the strength of the sample. In addition, the fibers could form a disordered network structure inside the matrix, disperse external force, weaken the stress concentration at the tip of internal cracks, and significantly improve the toughness of the modified sample. By incorporating 2.0% paraffin emulsion in the mortar and spraying 5 dilutions of sodium methyl silicate on the external surface, dense protective layers were formed both inside and outside the modified sample. The water absorption rate reduced from 30.27% to 23.30%, and the water resistance was increased to satisfy the specified requirement for the insulation material. Full article

This study explored the chloride binding characteristics and mechanisms of sulphoaluminate cement (SAC) by isolating its principal mineral component, anhydrous calcium sulphoaluminate (${\mathrm{C}}_4{\mathrm{A}}_3\stackrel{\mathrm{-}}{\mathrm{S}}$), as the research object. Chloride ingress was investigated under external penetration and internal incorporation conditions, with gypsum dosage varied at molar ratios of 1:0, 1:1, and 1:2 relative to ${ \mathrm{C}}_4{\mathrm{A}}_3\stackrel{\mathrm{-}}{\mathrm{S}}$. Through chloride binding experiments and hydration product analysis performed by XRD and TG, the following findings were obtained: under external chloride exposure, the binding capacity increased with rising solution concentration and immersion time. External chloride binding was attributed to SO₄²⁻/Cl⁻ ion exchange in AFm to generate Friedel’s salt and was complemented by physical adsorption of chloride in AH₃ gel. Under internal chloride incorporation, binding capacity increased progressively with curing age. Internal chloride binding involved the direct participation of Cl⁻ in hydration reactions to form Friedel’s salt in addition to the chemical reaction of AFm and the physical adsorption of AH₃. Gypsum dosage critically regulates the AFm/AFt ratio, which in turn governs chloride binding efficiency under both external and internal chloride scenarios (e.g., after immersion in 1 mol/L NaCl solution, the bound chloride content for ${\mathrm{C}}_4{\mathrm{A}}_3\stackrel{\mathrm{-}}{\mathrm{S}}$/gypsum ratios of 1:0, 1:1, and 1:2 was 50.94, 27.28, and 13.47 mg/g, respectively). Full article

Background: Osteoporosis screening in dental practice is challenging because dual-energy X-ray absorptiometry is not easily applicable to jaw bones. Objective: This study aimed to evaluate the diagnostic performance of a logistic regression model combining intraoral bone mineral density (BMD) using DentalSCOPE with the panoramic mandibular cortical index (MCI) for osteoporosis screening. Methods: Among 104 patients included in the study, 83 who underwent both intraoral and panoramic radiography were retrospectively selected as a training cohort to develop a logistic regression model for osteoporosis prediction. The mean age was 52.4 years, and 65.1% were female. Intraoral radiographs were analyzed using DentalSCOPE^® (Media Co., Tokyo, Japan) to determine BMD in the alveolar region (al-BMD). On panoramic radiographs, experienced radiologists determined the MCI. An additional 21 patients (mean age 63.1 years; 81.0% female) were prospectively enrolled as an external validation cohort. The trained model was applied to both the training (internal) and external cohorts to evaluate its diagnostic performance, which was compared with that of intraoral or panoramic radiography, using receiver operating characteristic (ROC) analysis. Results: In the training cohort, areas under the ROC curve (AUCs) of al-BMD and MCI were 0.74 and 0.82, respectively, while the combined model showed improved performance with an AUC of 0.88. In the external validation cohort, the AUCs were 0.92 and 0.97 for al-BMD and MCI, respectively. The performance of the combined model improved with an area under the AUC of 1.00. Conclusions: DentalSCOPE-based al-BMD, particularly when combined with panoramic MCI, offers a reliable and practical approach for opportunistic osteoporosis screening in dental care. Full article

This study explored the feasibility of utilizing tunnel muck-derived recycled granite aggregates (RGAs) in surface-layer asphalt mixtures via hybrid with basalt aggregates. Firstly, RGAs, including coarse aggregates (RGCAs) and fine aggregates (RGFAs), were prepared using a production method integrated with multi-cleaning technology. Then, the material properties of RGAs and RGA–basalt hybrid aggregates with varying RGA volume proportions were investigated. Finally, asphalt mixtures with these hybrid aggregates were designed and their engineering performance was evaluated. Basalt aggregates and their corresponding asphalt mixture served as the control group. Results suggest that since RGAs are rich in quartz and their SiO₂ content is as high as 70.88%, they are acidic aggregates. Employing multi-cleaning technology is a guaranteed method of obtaining RGAs with low mud content. The main conventional technical indexes of RGAs and all hybrid aggregates with 40–70% RGA volume proportions meet the requirements of Chinese technical specifications. Asphalt mixtures incorporating RGAs exhibit slightly higher voids in the mineral aggregates (VMAs) than the control group, indicating that RGAs modify the interlocking skeleton and contact states of aggregates. Blending RGAs with basalt to form hybrid aggregates is an effective way to achieve full-gradation utilization of tunnel muck-derived RGAs in the surface-layer asphalt mixtures. Without additional enhancement measures, a 40% RGA volume proportion in hybrid aggregates is recommended. For a higher RGA recycling rate, combining RGAs with cement is advised, maintaining 70% RGA volume proportion and 50% cement content of total filler volume. When external basalt aggregates are transported over a distance of 50–200 km, applying these schemes to local asphalt pavement surface layers can achieve at least 26.56% aggregate cost savings. Full article

This study explores the visible-light-driven photolysis of Ferrioxalate complexes for the degradation of Toluidine Blue (TB), a persistent phenothiazine dye, using a 1 L recirculating batch-loop photoreactor. The reactor system incorporated two tubular photochemical units (35 cm × 3 cm each) in series: the first equipped with an immersed blue fluorescent lamp (12 W, 30 cm-tube), and the second with dual external blue LED lamps (18 W total, 30 cm) encasing a double-walled glass cell. Continuous flow between the units was maintained via a peristaltic pump. Experimental investigations were used to evaluate the effects of key parameters such as Fe(III) and oxalate concentrations, initial TB load, pH, light source, flow rate, ligand type, dissolved gas type, external H₂O₂ addition, and the presence of various inorganic ions. The results demonstrate efficient dye degradation, with ~75% TB removal within 1 h under combined fluorescent and LED irradiation, where each reactor contributing comparably. The optimal performance was achieved at pH 4, with a 10 oxalate-to-Fe(III) molar ratio (1 mM:0.1 mM) and a flow rate of 25 mL s⁻¹. Among various ligands tested (oxalate, acetate, citrate, EDTA), oxalate proved to be the most effective. The presence and type of anions significantly influenced degradation efficiency due to their potential scavenging effects. Although the process achieved high dye removal, TOC analysis indicated only moderate mineralization, suggesting the accumulation of non-colored intermediates. External H₂O₂ addition moderately improved TOC removal, likely due to enhanced hydroxyl radical generation via the Fenton mechanism. These findings highlight the promise of Ferrioxalate-based photochemical systems under visible light for dye removal, while also emphasizing the need for further research into by-product identification, mineralization enhancement, and toxicity reduction to ensure safe effluent discharge. Full article

For mineral exploration, an increasing number of geophysical instruments have adopted unmanned aerial vehicles (UAVs) as their carrier platforms. The effective fusion of multi-modal geophysical information will be conducive to further enhancing the reliability of exploration results. However, the integration degree of UAVs and geophysical equipment is still low, and the advantages of UAVs as robots have not been fully exploited. In addition, the existing fusion methods are still difficult to use to establish the spatial distribution model of ore-bearing rock. Therefore, we reviewed the development status of UAVs and the geophysical instruments. We believe that only by integrating the system, designing the observation plan in accordance with the requirements of the fusion method, and treating the hardware part as an external extension of the algorithm, can high-matching data be provided for fusion. Subsequently, we analyzed the progress of the fusion methods, leading us to believe that the cross-dimensional and cross-abstract-level issues are major challenges in the algorithm aspect. Meanwhile, the fusion should be carried out simultaneously with the generation of the ore-bearing rock model, that is, to establish an integrated system of fusion and generation. It is hoped that this research can promote the development of UAV-borne multi-modal observation technology. Full article