Search Results (607)

Zeolitic imidazolate framework-8 (ZIF-8) has emerged as a material for electrochemical energy conversion, serving dual primary roles in fuel cell technologies: (i) as an electrocatalyst precursor for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) through pyrolysis-derived N-doped porous carbons and metal–nitrogen–carbon (M–N–C) structures, and (ii) as a membrane component that enhances proton conductivity via imidazole-mediated Grotthuss hopping while suppressing fuel crossover through molecular sieving. This comprehensive review systematically evaluates ZIF-8 performance across multiple fuel cell types, including primarily proton exchange membrane fuel cells (PEMFCs), as well as direct methanol fuel cells (DMFCs), anion exchange membrane fuel cells (AEMFCs), and microbial fuel cells (MFCs), while also covering related electrochemical applications such as zinc–air batteries, supercapacitors, and water splitting devices, where ZIF-8-derived materials demonstrate improved catalytic activity. The review examines structure–performance relationships, highlighting strategies such as heteroatom doping, bimetallic synergy, hierarchical porosity engineering, and polymer composite fabrication that have enabled ZIF-8-based catalysts to achieve ORR half-wave potentials and PEMFC power densities, rivaling commercial Pt/C systems. ZIF-8 composite membranes demonstrate proton conductivities in polybenzimidazole systems and effective methanol blocking. Despite improved progress, challenges persist regarding long-term stability, scalable synthesis, and degradation mechanism understanding. This review critically analyzes recent advances, identifies performance-limiting factors across applications, and outlines future research directions for developing commercially viable ZIF-8-based electrochemical technologies. Full article

In the primary spruce-fir-Korean pine forest affected by historical windthrow, soil water-holding capacity shows complex spatial associations with forest microenvironment and soil physicochemical properties. However, its spatial variability and multi-factor hierarchical association pathways remain poorly understood. Taking the primary spruce-fir-Korean pine forest on a historically windthrow-affected site in the Liangshui National Nature Reserve, Xiaoxing’an Mountains, China as the research object, geostatistics and partial least-squares structural equation modeling were used to analyze the spatial pattern of topsoil (0–20 cm) water-holding capacity and its environmental association pathways. The results showed saturated, capillary and field water-holding capacities of topsoil exhibited moderate variability and strong spatial autocorrelation (all nugget to sill ratios < 25%), showing a patchy distribution. No significant direct association was detected between windthrow mechanical disturbance intensity and topsoil water-holding capacity. Bulk density (path coefficient = −0.685, p < 0.001) and soil porosity (path coefficient = 0.273, p < 0.001) had significant direct associations with soil water-holding capacity, whereas soil particle size distribution showed no significant effect (p > 0.05). Canopy structure and understory microclimate exerted indirect associations with soil water-holding capacity via soil structure; litter showed no significant associative effect (p > 0.05). These results indicate that soil water-holding capacity on the historically windthrow-affected site was not randomly distributed, but presented an ordered patchy pattern closely related to in-plot micro-environmental factors. Full article

The main objective of this systematic review was to synthesise current knowledge on tricalcium phosphate (TCP) as a functional modifier of poly(methyl methacrylate) (PMMA)-based bone cements, relating the microstructure of PMMA/TCP composites to their mechanical, biological and functional (handling) performance. Web of Science, Scopus and PubMed were searched for 2010–2025. Studies reporting primary quantitative data on PMMA cements specifically modified with TCP were eligible. Over one hundred records were screened by two independent reviewers, yielding 15 studies appraised qualitatively and combined by narrative synthesis. The evidence links polymerisation of the PMMA matrix, calcium and phosphate ion release from TCP, apatite-layer precipitation, and cell-mediated TCP resorption coupled to bone remodelling. TCP, especially β-TCP or biphasic calcium phosphate systems, can balance mechanical stability with bioactivity: moderate β-TCP contents (of the order of 10 wt% for solid cements under quasi-static compression) preserve clinically acceptable properties while enhancing osteoconductivity, though this limit falls for porous, α-TCP-containing and fatigue-loaded formulations. Porosity, TCP amount, crystalline form and particle size are the governing microstructural variables. The evidence is limited, dominated by in vitro and short-term static tests, with heterogeneous formulations and no controlled clinical data, so benefits should be interpreted qualitatively rather than as firm quantitative relationships. The review was not registered; this research received no external funding. Full article

Background: Optimal porosity and surface area of additively manufactured Ti-6Al-4V scaffolds for early human mesenchymal stem cell (hMSC) retention remain unclear, despite their importance in reconstruction of critical-sized bone defects. This study evaluated scaffold architectures fulfilling biomechanical criteria for hMSC and osteocyte survival, proliferation, differentiation, cell cycle, and retention. Methods: Primary hMSCs from four healthy donors were characterized by flow cytometry, immunofluorescence, and Western blotting. Cells were seeded onto Ti-6Al-4V scaffolds with graded porosity (P50–P90, 50–90% porosity) and cultured for 120 h. Viability and retention were measured by trypan blue exclusion, apoptosis and cell cycle by flow cytometry, and osteogenic differentiation by collagen I, osteocalcin, and Akt phosphorylation analyses. Collagen-embedded hMSCs and osteoblasts were used to assess migration and phenotype maintenance. Results: The densest scaffold, P50, consistently retained significantly more viable hMSCs and differentiated osteoblasts than P60 and P70 (p < 0.005 in both cases, One-way ANOVA analysis, significance level a = 0.05 followed by Bonferroni correction). Among the scaffold architectures investigated, P50 demonstrated the most favorable early cellular retention under the present experimental conditions. No scaffold-induced apoptosis or proliferation changes were detected. Osteogenic differentiation and Akt phosphorylation increased during culture. In collagen-containing scaffolds, cells migrated from the matrix and preferentially coated titanium struts, with P50 supporting superior attachment. Conclusions: Among the scaffold architectures investigated, the low-porosity/high-surface-area P50 design provided the most favorable early microenvironment for hMSC and osteoblast retention without cytotoxic effects. Full article

The accumulation of dissolved species during the in situ leaching (ISL) of uranium can lead to ore-layer blockage and reduced production capacity. Clay minerals, including montmorillonite, chlorite, kaolinite, and illite, are the primary cementing and filling materials in sandstone-hosted uranium deposits in China. However, previous studies have predominantly focused on the leaching behavior of uranium minerals, while systematic investigations into the dissolution mechanism of clay minerals under CO₂+O₂ conditions remain scarce. In this study, laboratory dissolution experiments, scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), computed tomography (CT) scanning, and field verification were conducted to systematically investigate the dissolution behavior of major clay minerals and their contribution to ore-layer blockage under CO₂+O₂ leaching conditions. The results indicate the following: (1) Montmorillonite exhibited the most significant dissolution, with granular deposits rich in Ca and Si formed on its surface, which were inferred to be Ca-Si-rich precipitates. (2) Obvious changes in both microstructure and macroscopic physical properties of clay minerals were observed before and after leaching, with porosity decreasing by approximately 12.96% and permeability decreasing by approximately 10.16%. (3) Field verification revealed that the scale in the ore layer, filter cloth blockage, and resin surface caking were primarily composed of silica gel and hydroxide/carbonate precipitates of Al, Ca, and Fe, which are closely related to the dissolution and leaching of clay minerals. This study confirms that montmorillonite is the main source of clogging substances, and long-term closed circulation of injection and extraction leads to the accumulation of precipitates, exerting a significant impact on the uranium-leaching system. The findings provide a theoretical basis for anti-clogging and permeability enhancement in CO₂+O₂ ISL operations. Full article

Gel-based novel drug delivery systems (NDDS) occupy a mechanistically distinct niche among controlled-release platforms because they decouple three design variablesnetwork cross-link density, continuous-phase polarity, and stimulus sensitivitythat in particulate carriers (liposomes, polymeric nanoparticles) are often interdependent. This critical review synthesizes 102 primary and secondary sources published predominantly between 2010 and 2026 to interrogate, rather than merely catalog, how hydrogels, organogels, aerogels, nanogels, in situ gelling systems, and hydrogel-forming microneedles have been engineered for site-specific pharmacotherapy. Beyond a taxonomic overview, the review quantitatively contrasts formulation parameters sol–gel transition temperatures (typically 32–37 °C for poloxamer 407/188 systems), swelling ratios, mesh sizes, and reported drug-release half-lives across oncology, chronic diabetic wound care, ophthalmic and nasal-to-brain delivery, musculoskeletal (intra-articular) therapy, subunit vaccine depots, periodontal pocket therapy, and glucose-responsive insulin delivery. Particular attention is paid to the mechanistic basis of burst release, the porosity–mechanical-integrity trade-off inherent to interconnected hydrogel networks, and the divergence between preclinical rodent efficacy and the comparatively sparse controlled human trial data available for most gel platforms. The review concludes that while stimuli-responsive and 3D/4D-printed gel architectures have matured substantially as engineering constructs, clinical translation remains bottlenecked less by materials science than by inconsistent characterization standards, unresolved terminal-sterilization compatibility, and a paucity of head-to-head comparative trials against existing standard-of-care formulations. Full article

Electric aviation and unmanned aerial vehicles (UAVs) depend on lightweight composites to preserve payload and range, yet mass reduction, recycled content, or bio-based content alone does not establish component suitability. Candidate systems must also satisfy coupled structural, thermal, fire, electrical, manufacturing, durability, repair, and circularity requirements. This structured critical narrative review evaluates thermoplastic carbon-fibre-reinforced polymer (CFRP) systems, recycled-carbon-fibre composites, natural-fibre systems, bio-based and recyclable matrices, hybrid architectures, and multifunctional composites using a component-specific framework based on source role, evidence maturity, test comparability, and failure consequence. The framework links processing and chemistry to defects, retained performance, repair and recovery, and the evidence required for defined aircraft and UAV components. Thermoplastic CFRP provides the strongest near-term pathway for secondary and semi-structural components, although weld durability, impact tolerance, fire response, and process conformity remain system specific. Recycled-carbon-fibre and natural-fibre systems are most defensible for lower-consequence covers, fairings, housings, interiors, and UAV parts when feedstock variability, moisture, porosity, and fire performance are controlled. Battery enclosures, primary structures, rotor-support members, and structural-battery systems require representative coupled-hazard and component-scale evidence. The resulting adoption pathways are bounded by component and operating conditions, with manufacturing, durability, repair, recovery, and qualification evidence specified for each application. Full article

This pilot in vitro study explored the tensile retention of lithium disilicate and monolithic zirconia crowns cemented onto zirconia one-piece implants using two resin cements and two cementation protocols. In addition, the relationship between micro-computed tomography (micro-CT)-derived cement layer characteristics and retention was explored for lithium disilicate crowns. Thirty-two implant–crown assemblies were prepared using 16 lithium disilicate and 16 zirconia crowns. Specimens were cemented with either an adhesive resin cement (Panavia V5) or a self-adhesive resin cement (SpeedCem Plus) using two protocols: conventional apical-half cementation (AH) and an abutment-assisted apical-half protocol (A-AH). Cement thickness and porosity for lithium disilicate crowns were obtained from a previously published micro-CT analysis of the same specimens; no micro-CT measurements were available for the zirconia specimens. Tensile pull-out testing was performed using a universal testing machine. The primary outcome was the maximum recorded force at the first observed mechanical failure, irrespective of the mode of that failure, so that all 32 specimens contributed a value. Failure occurred by crown debonding in 27 specimens, by crown fracture in 4 and by implant fracture in 1. For the primary outcome, the maximum recorded force was lower for lithium disilicate than for zirconia crowns (medians 347.20 versus 596.05 N; exact Mann–Whitney p = 0.017) and lower with the A-AH than with the AH protocol (medians 304.24 versus 614.38 N; p < 0.001), whereas the difference between the two resin cements was not statistically significant (medians 438.88 versus 550.83 N; p = 0.210). The highest observed mean maximum load was recorded for zirconia crowns cemented with Panavia V5 using the AH protocol (729.9 ± 237.7 N), whereas the lowest observed mean maximum load was recorded for lithium disilicate crowns cemented with Panavia V5 using the A-AH protocol (219.7 ± 105.1 N). In a secondary, cause-specific exploratory analysis restricted to crown debonding (27 events, 5 specimens censored at fracture), Cox proportional hazards regression on the applied-force scale gave hazard ratios of 3.75 (95% CI 1.40–10.01) for lithium disilicate versus zirconia, 6.47 (2.39–17.53) for A-AH versus AH and 1.82 (0.76–4.39) for Panavia V5 versus SpeedCem Plus. For lithium disilicate crowns, exploratory factorial ANOVA indicated that cementation protocol was associated with differences in cement thickness (p = 0.035), while cement type was associated with differences in porosity (p < 0.001). All 16 lithium disilicate cement thickness observations lay between 253.29 and 254.96 µm, a total span of 1.67 µm. Within that extremely restricted range, a univariable exploratory Cox model expressed per 0.1 µm gave a hazard ratio for debonding of 1.24 (95% CI 1.03–1.48; p = 0.024); this is an unadjusted association across a range that is itself associated with cementation protocol, and it does not demonstrate a clinically meaningful or independent effect of cement thickness. No association was detected for total porosity (0.959 per percentage point, 0.717–1.283); that interval is wide and indicates absence of evidence rather than evidence of no association. Within the limitations of this pilot in vitro study—four specimens per subgroup, wide confidence intervals and no adjustment for multiplicity—the findings suggest that crown material and cementation protocol may be associated with retention patterns. They are exploratory and hypothesis-generating and require confirmation in larger, independently powered studies. Full article

The characterization of geothermal reservoirs and their genetic mechanisms is critical for understanding geothermal system evolution and evaluating geothermal resource potential. The eastern Gushi Sag of the Weihe Basin hosts three Neogene sandstone geothermal reservoirs, including the Gaoling Group, Lantian–Bahe Formation, and Zhangjiapo Formation; however, their reservoir characteristics and genetic mechanisms remain poorly constrained. This study integrates geological structures, geothermal well logging, core petrophysical properties, and hydrochemical data to characterize reservoir conditions and establish a genetic model. The results show that the Neogene reservoirs are mainly composed of feldspathic sandstone, with the Lantian–Bahe Formation identified as the primary geothermal reservoir due to its moderate porosity, low permeability, large sandstone thickness, and favorable continuity. The geothermal field exhibits an average geothermal gradient of 3.35 °C/100 m with a south-to-north decreasing trend. Hydrochemical evidence suggests that geothermal fluids originate mainly from meteoric water recharged from the northern Qinling Orogenic Belt and paleo-sedimentary water, with deep faults and pore networks controlling fluid migration and accumulation. The Quaternary strata and Zhangjiapo Formation provide effective sealing conditions. This study reveals the coupled controls of thermal conditions, reservoir architecture, fluid circulation, and preservation on sandstone geothermal systems, providing insights into geothermal resource assessment, exploration strategy optimization, and the formation mechanisms of similar sedimentary basin geothermal systems. Full article

This study reported on the multi-objective optimization of atmospheric plasma spraying parameters for zirconia coatings by incorporating the response surface method with the desirability method, while simultaneously enhancing microhardness and reducing wear rates. The spraying variables were optimized to improve coating performance using an L18 Taguchi orthogonal experimental design combined with the response surface method. The analysis of variance revealed the primary factors to be acceleration voltage, stand-off distance, powder feed rate, and primary gas Ar/H₂; together, these factors accounted for 79.70% of the total performance variance. An R² value of 0.752 for microhardness was yielded by the fitted reduced quadratic model, whereas an R² value of 0.845 for wear volume losses was yielded by the interaction model. Within the optimised parameter range, the predicted microhardness was 1404.1 HV, with an experimental error of only 1.84%, and the wear volume loss was reduced to 4.53 mm³, with a prediction error of 3.27%. Additionally, the optimized coating was found to have fully molten droplets, less porosity, and negligible interlayer cracks, with only slight pitting observed during the wear test, as revealed by scanning electron microscopy. This multi-objective optimisation strategy, integrating the Taguchi method with the RSM, effectively enables the preparation of zirconia coatings with superior mechanical properties and provides reliable process guidelines for protective coatings on aluminium alloys. Full article

Chemical glycolysis can convert waste poly(ethylene terephthalate) (PET) into bis(2-hydroxyethyl) terephthalate (BHET), but recyclable heterogeneous catalysts derived from circular carbon sources and showing low metal release remain limited. Here, post-consumer expanded polystyrene (EPS) was transformed into a hypercrosslinked polymer (HCP) and carbonized with Fe to produce Fe@graphitic-carbon (Fe@C) catalysts for PET glycolysis. The catalysts are denoted mFe@EPS-HCP₈₀₀, where m represents the nominal Fe loading (wt.%), and 800 is the carbonization temperature (°C). The optimized 5Fe@EPS-HCP₈₀₀ contained graphitic carbon layers, bamboo-like carbon nanotube (CNT) domains, hierarchical porosity, and Fe-rich domains associated with graphitic carbon coverage. Under atmospheric-pressure conditions (PET, 2.00 g; ethylene glycol, 20.00 g; catalyst, 0.20 g; 200 °C; 2 h), it achieved complete PET conversion and 94.6% BHET yield. The catalyst also maintained BHET yields of ca. 90–94% over ten reuse runs, and post-reaction microscopy confirmed the retention of graphitic carbon layers and Fe-containing domains. Fe was below the detection limit in the product solutions for the 1, 3, and 5 wt.% Fe catalysts, whereas 7Fe@EPS-HCP₈₀₀ released 9.1 mg kg⁻¹ Fe, consistent with incomplete carbon coverage at excessive Fe loading. Conversion profiles followed an Avrami–Erofeev/Weibull model, giving an apparent activation energy of 205.6 kJ mol⁻¹. The data support a two-stage pathway in which external graphitic carbon/CNT domains promote primary PET chain scission to soluble oligomers, followed by Fe@C interfacial secondary glycolysis to BHET. This work demonstrates dual waste-polymer valorization by using EPS waste as catalytic infrastructure for PET chemical recycling. Full article

The deep to ultra-deep sandstone reservoirs of the Cretaceous Bashijiqike Formation in the Kelasu structural belt of the Kuqa Depression exhibit strong heterogeneity. This study integrates single-well stress calculation, image log fracture interpretation, thin-section petrographic analysis, and porosity–permeability testing to compare stress, fracture, and reservoir characteristics across the Dabei–Bozi cross-section. The results show that the northern stress release zone is characterized by low S_H (98 to 148 MPa) and E (9220 to 23,420 MPa), indicating weak cumulative stress, low effective fracture density (0.09 fractures/m), and primary-pore dominated reservoirs. The central stress transition zone has progressively increasing S_H (136 to 187 MPa) and E (27,450 to 33,210 MPa) from north to south, indicating strong cumulative stress, high effective fracture density (0.31 fractures/m), and mixed primary–secondary pore-fracture reservoirs. The southern stress accumulation zone shows increasing S_H but decreasing E to the south, indicating that the late-stage high stress results in low effective fracture density (0.08 fractures/m) and preserving primary pores. These results demonstrate that reservoir quality is governed by the cumulative effect of the stress field, rather than by present-day stress or peak paleo-stress alone. This reservoir distribution model could provide a theoretical basis for reservoir prediction in the foreland basin. Full article

Turbidite sandstones of the Chang 6 member and delta-front sandstones of the Chang 8 member in the Yuele Block, southwestern Yishan Slope, Ordos Basin, serve as the primary tight oil reservoirs. In this study, a total of 243 continuous core samples from multiple wells were collected for integrated analyses, including cast thin-section observation, scanning electron microscopy (SEM), X-ray diffraction (XRD) of clay minerals, routine core physical property measurements and mercury intrusion porosimetry (MIP), to systematically compare sedimentary–diagenetic disparities between semi-deep lacustrine turbidites (Chang 6) and delta-front sandstones (Chang 8). Measured data indicate that the two intervals have similar average porosities of 9.27% and 9.88%, while their respective geometric mean permeabilities differ markedly, with values of only 0.142 × 10⁻³ μm² for Chang 6 and 0.260 × 10⁻³ μm² for Chang 8. Micro-pore-throat size and connectivity dominate reservoir fluid flow capacity, and total porosity alone cannot objectively evaluate reservoir quality. Delta-front sandstones of the Chang 8 member are supplied by a proximal magmatic-rich provenance from the southwest, and widespread grain-coating chlorite forms during early diagenesis, effectively mitigating compaction damage and inhibiting quartz overgrowth, leading to well-preserved primary pores. As mixed-provenance deposits lacking protective chlorite rims, Chang 6 turbidites experience more intensive compaction, and abundant fibrous illite and carbonate cements precipitate in the subsequent diagenetic stage to fill and separate pore throats, forming an isolated micropore network. Quantitative comparison with baseline parameters of the Longdong region reveals that the Yuele Block is located closer to the southwestern sediment source, resulting in higher contents of magmatic lithics and chlorite in Chang 8 as well as elevated illite concentrations in Chang 6 relative to regional averages, which verifies that source-to-sink transport distance regulates reservoir quality by driving the differentiation of clay mineral assemblages. A complete quantitative coupling sequence of “provenance supply–authigenic clay mineral-pore evolution” is defined herein, and two distinct sedimentary–diagenetic evolutionary routes are classified: high-quality delta-front reservoirs protected by grain-coating chlorite, and low-quality turbidite reservoirs blocked by illite–carbonate cements. This research refines the diagenetic differentiation rules for continental tight sandstones with diverse sedimentary origins in the Ordos Basin and provides quantitative mineralogical criteria for identifying tight oil sweet spots in proximal provenance blocks. Full article

Rhizobial inoculants play a critical role in sustainable agriculture by enhancing biological nitrogen fixation; however, maintaining rhizobial viability during storage remains a formidable challenge. In this paper, six embedded rhizobial formulations, designated E-SA/PVA R1 through E-SA/PVA R6, were prepared via an embedding method using sodium alginate (SA), polyvinyl alcohol (PVA), and eggshell powder as primary materials with varying component ratios. Structural characterization confirmed the suitability of the composite hydrogel carriers for rhizobial encapsulation: Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) revealed effective crosslinking between SA and PVA, yielding a stable matrix. Scanning electron microscopy (SEM) confirmed the successful encapsulation of abundant rhizobia within the carriers. Mercury intrusion porosimetry (MIP) was employed to characterize the pore architecture of the composite carriers, revealing the relationships among porosity, average pore size, and permeability. Mass transfer evaluation using three probe molecules of differing molecular weights yielded diffusion permeability coefficients (DPC) that quantitatively elucidated the size-dependent transport behavior within the carrier matrices. All embedded formulations displayed favorable biodegradability in soil environments. Notably, the embedded agents maintained viable cell counts above 8 log CFU/g across all formulations even after 60 days under various pH and temperature conditions, satisfying the microbial fertilizer standard in China, establishing them as promising candidates for practical rhizobial inoculant applications. Full article

The circular economy increases the importance of quality and traceability in functional materials produced from industrial, municipal, and agricultural waste. However, the selection of Industry 4.0 (I4.0) technologies in waste valorization remains unsystematic and weakly linked to material and process requirements. This study develops a decision-support model for selecting I4.0 solutions for quality assurance and traceability in the production of waste-derived functional materials. The model was grounded in a two-track scoping review reported according to PRISMA-ScR. Track A mapped the functions of I4.0 technologies in quality control and manufacturing traceability, while Track B identified challenges related to waste-derived biopolymers, composites, sorbents, catalysts, and nanomaterials. Among 322 primary material studies, microstructure, morphology, and porosity dominated (69.9%), whereas traceability was underrepresented and requires further validation. In Track A, 629 studies were unambiguously mapped, with inspection and monitoring as the dominant functions. Material-specific challenges were then linked to required functions and candidate technologies, which were ranked by their fit to the decision situation and literature support. The resulting model covered 48 material situations and 95 function–technology pairs. It supports technology selection based on material category, waste type, process stage, and quality or traceability requirements rather than technology availability alone. The proposed approach may be extended to waste-derived materials for other application sectors, including construction and transport, subject to sector-specific, material-specific, and industrial validation. Full article