Search Results (574)

This study focuses on the mechanical properties and durability performance of polypropylene (PP) fiber incorporated into M25-grade concrete using sustainable waste materials such as microsilica (MS) and grounded e-waste (EW). Cement is partly replaced with varying proportions of MS starting from 0 to 15% in the concrete mix. Ground waste printed circuit board (PCB) is utilized as the partial replacement for fine aggregate with varying content from 0 to 45%, addressing a major environmental issue related to EW disposal. Additionally, PP fiber content is varied from 0 to 0.6% to improve the strength and toughness characteristics of concrete. The mechanical properties and durability analysis of the samples are conducted to assess the performance of concrete containing MS, EW, and fibers. Optimization of these ingredients was carried out through design of experiments (DoE). The experimental validation mix (MEV) achieved a 28-day compressive strength of 33.66 MPa comparable to the control mix (M0) (35.76 MPa), exceeding the target design strength. The MEV mix exhibited enhanced durability, with the reduction in RCPT value attributed to the low chloride ion penetrability. Meanwhile, sulphate-induced compressive strength loss was diminished by 38% for MEV compared to the control mix, indicating improved stability against acid attacks. This work sheds light on the inclusion of these sustainable materials as a potential pathway to achieve superior mechanical and durability properties for concrete, providing a sustainable solution to the recycling of PCB e-waste. Full article

Polymeric antistatic additives offer improved resistance to migration compared with low-molecular-weight agents, but high loadings are generally required to establish effective charge-dissipation pathways in nonpolar polypropylene (PP). Herein, a series of quaternary ammonium salt-functionalized polyamide 6/polyethylene glycol elastomers (QASPA6PEG) was synthesized by melt copolymerization and used as multifunctional antistatic additives for PP. Increasing the nominal QAS content decreased the surface resistivity of the elastomers from 3.24 $\times$ 10⁹ Ω to 9.71 × 10⁸ Ω. The elastomers were subsequently melt-blended with PP at loadings of 10–20 wt% using maleic-anhydride-grafted polypropylene as a compatibilizer. The surface resistivity of the blends decreased with increasing QAS content and elastomer loading, consistent with the formation of increasingly interconnected ion-conducting domains. The blend containing 20 wt% 0.4QASPA6PEG exhibited surface resistivities of 3.64 $\times$ 10¹¹ Ω and 4.69 $\times$ 10¹⁰ Ω on days 0 and 60, respectively. Its saturated water absorption reached 4.38%, compared with 0.27% for neat PP, supporting a moisture-assisted ionic conduction mechanism. The measured bromine content remained nearly unchanged after 60 days of storage, indicating limited loss of the QAS-containing component. In addition to improving charge dissipation, QASPA6PEG enhanced the ductility and impact resistance of PP. At a loading of 20 wt%, 0.4QASPA6PEG increased the elongation at break from 358 ± 23% to 690 ± 81% and the notched impact strength from 3.16 ± 0.37 to 4.93 ± 0.45 kJm⁻². These results demonstrate that covalently introducing ionic structures into PA6/PEG elastomers is an effective strategy for coupling antistatic modification with toughening in PP. Full article

The sturdy and stable unique polyhedral structure of FeOOH nanoparticles facilitates stress and load transfer, thereby forming a tighter mechanical interlock at the carbon fiber–matrix interface. In this work, the FeOOH nanocrystal layer in situ grown on flexible carbon fiber cloth was rationally designed and fabricated through hydrothermal synthesis. Then, the non-covalent cation–π bond was constructed at the interface between the iron ion-loaded FeOOH nanoparticles and indole-based poly(hexahydrotriazine) (In-PHT). Owing to the collaborative effects of physical anchoring and chemical bonding, the resultant composite exhibited an outstanding tensile strength of 322 MPa, and the friction coefficient significantly decreased by 63% compared with the composites without FeOOH nanoparticles. Moreover, the resultant worn composite showed an excellent self-healing property owing to the introduction of polyethylene wax (PEW) with a low melting point, and the healed friction coefficient remained almost unchanged. Extensive analyses verify that the phase-separated structure and Fe³⁺–π interactions across multiscale interfaces achieve the combined advantages of wear resistance and durability for recyclable carbon fiber-reinforced poly(hexahydrotriazine) composites (PHT-CFRPs). Full article

The durability of alkali-activated materials (AAMs) in acidic environments is a key factor governing their suitability as sustainable alternatives to ordinary Portland cement (OPC). This study investigates the acid resistance of fly ash–slag alkali-activated mortars prepared with either seawater-based or distilled water-based activator solutions, thereby addressing the feasibility of substituting potable water in activator preparation. Eleven binder blends were tested, ranging from 100% fly ash (F100G0) to 100% ground granulated blast furnace slag (GGBS, F0G100) in 10% replacement increments, each prepared with both distilled-water (D-series) and seawater-based (M-series) activator solutions. Mortar cubes were exposed to hydrochloric acid (HCl) and sulphuric acid (H₂SO₄) after curing for 28, 60, 90, and 180 days. Durability was assessed through mass change, compressive strength retention, and ultrasonic pulse velocity (UPV), complemented by X-ray diffraction (XRD) analysis to elucidate mineralogical transformations. Results showed that acid resistance was governed primarily by binder composition: calcium-rich slag (C–A–S–H) systems deteriorated mainly by decalcification under acid exposure, whereas low-calcium fly ash (N–A–S–H) systems degraded more slowly by dealumination. Seawater activation did not significantly compromise acid resistance relative to distilled-water systems, with the two-activator series performing comparably under both HCl and H₂SO₄. Paired comparisons of the reported blend values showed small, age-dependent differences between the two-activator series: seawater activation modestly delayed strength loss under HCl at intermediate ages, while under H₂SO₄ it carried a small late-age penalty attributable to reaction of activator-derived chloride compounds with the acid; at most ages, the two series were statistically indistinguishable. X-ray diffraction showed essentially identical phase assemblages in the two series: no crystalline products formed under HCl, where an amorphous silica-rich residue accumulates on fly-ash-rich blends, whereas gypsum was the sole crystalline product under H₂SO₄, enhanced in seawater-activated fly-ash-rich blends. The findings clarify the role of marine ions in influencing acid degradation and provide guidance for designing sustainable binder systems for chloride- and sulphate-rich service environments. Overall, seawater is shown to be a viable substitute for potable water in activator preparation, retaining acid resistance comparable to distilled-water systems and supporting the development of more sustainable alkali-activated binders. Full article

Heavy metal fluoride glasses (HMFGs), particularly fluorozirconate glass systems such as ZBLAN have attracted considerable attention due to their unique physical properties, including low phonon energies, wide transparency from the UV to the mid-IR, and high rare-earth ion doping solubility, making them promising materials for photonic applications. This review provides an overview of fluoride glass synthesis methods, structural characteristics, and physical properties of fluorozirconate glasses, with emphasis on glass processing conditions, thermal, mechanical, and optical properties. The structural characteristics are discussed in terms of zirconium–fluorine polyhedral networks and their compositional dependence, while physical properties are analyzed, including glass transition behavior, crystallization tendency, elastic moduli, and infrared transmission. Rare-earth doped Er³⁺, Ho³⁺, and Tm³⁺ ZBLAN glasses are also discussed, which exhibit efficient emissions in the near and mid-IR spectral regions. Although significant progress has been achieved, limitations related to thermal stability, mechanical strength, and incomplete understanding of structure–property relationships persist. Future research should therefore focus on compositional optimization and predictive structural modeling to enable the design of improved fluoride glasses for various applications. Full article

Long-chain n-alkane hydroisomerization is a key catalytic route for upgrading wax-rich, bio-derived, and synthetic hydrocarbon feedstocks into diesel fuels, sustainable aviation fuels, and lubricant base oils with improved low-temperature properties. However, selective hydroisomerization remains challenging because mismatches in the spatial proximity and relative strength of metal and acid sites can prolong the residence time of olefin/carbenium-ion intermediates, thereby promoting over-isomerization to multibranched species, deep cracking, and coke formation. This review summarizes recent advances in zeolite-based bifunctional catalysts for long-chain n-alkane hydroisomerization. The catalytic mechanisms are first discussed, including metal-catalyzed dehydrogenation/hydrogenation, acid-catalyzed skeletal rearrangement, and shape-selective pathways governed by pore-mouth and key-lock effects. Catalyst construction strategies are then outlined, with emphasis on the preparation of zeolite supports and the introduction and localization of metal sites. Subsequently, structure–performance relationships are reviewed from the perspectives of support properties, metal site characteristics, and promoter effects, followed by a concise assessment of catalyst performance with real feedstocks under industrially relevant conditions. Finally, this review provides guidance for the precise design of metal–acid bifunctional hydroisomerization catalysts by highlighting descriptor-guided optimization, spatially regulated metal–acid–pore architectures, multiscale characterization and modeling, and scalable catalyst construction under practical reaction conditions. Full article

Objective: To investigate the effect of milk minerals on bone mineral density (BMD) and bone quality in growing rats and explore the underlying mechanisms related to calcium absorption, bone metabolism, and the gut–bone axis. Methods: Sixty healthy 4-week-old male Sprague-Dawley (SD) rats were randomly divided to five groups based on their body weight: Low-Calcium Control Group (Control), Low-Dose milk mineral Group (Low), Medium-Dose milk mineral Group (Medium), High-Dose milk mineral Group (High) and Calcium Carbonate Control Group (CaCO₃), which received the same dose level (elemental calcium) as the High group. The milk mineral dosage was set at 5, 10, and 15 times the human recommended intake of elemental calcium. After 12 weeks of intervention, femurs were collected for analysis of BMD, bone microstructure, and bone mechanical strength. Additionally, analyses included calcium levels in the femur, feces, and diet; serum bone metabolism biomarkers; tissue protein expression; as well as gut microbiota composition and short-chain fatty acid content. Result: Milk mineral exhibited non-inferior efficacy to CaCO₃ in increasing femoral calcium content, enhancing BMD, and improving bone microarchitecture. Notably, the Medium group achieved comparable bone-protective effects to the CaCO₃ group despite a 20.8% lower calcium content, which was accompanied by a relatively high calcium absorption rate (90.9% vs. 86.5%). With respect to serum markers, milk mineral maintained bone formation while suppressing bone resorption, resulting in a net anabolic state comparable to that of CaCO₃. Milk mineral significantly upregulated the protein expression of renal CYP27B1 and intestinal calcium ion transporters, and increased serum IGF-I levels. Furthermore, milk mineral promoted the enrichment of certain specific gut microbial genera, which showed a significant positive correlation with IGF-I, bone calcium content and BMD. Conclusions: Milk mineral supplementation appears to promote bone formation and mineralization in growing rats, accompanied by enhanced intestinal calcium absorption, enrichment of characteristic gut microbes and elevated microbial metabolite concentrations. Full article

Carboxymethyl cellulose (CMC)-based solid polymer electrolytes (SPEs) have attracted significant attention as sustainable alternatives to conventional liquid electrolytes due to their biodegradability, non-toxicity, and excellent film-forming capability. However, pristine CMC suffers from inherent limitations, including low ionic conductivity, poor mechanical strength, and limited electrochemical stability. This systematic literature review comprehensively evaluates recent advances in CMC-based SPEs, focusing on the roles of lithium salts (e.g., LiCH₃COO, LiClO₄, LiI, LiBF₄, and LiNO₃) and functional additives, including plasticizers, ionic liquids, nanofillers, and cross-linking agents, in tailoring the physicochemical and electrochemical properties. The findings reveal that ionic conductivity can be significantly enhanced from ~10⁻⁷ to 10⁻² S cm⁻¹ through synergistic modifications that reduce crystallinity and promote segmental mobility. Electrochemical stability is improved by up to ~3.85 V with the incorporation of ionic liquids, while ion transference numbers approaching unity (t⁺ ≈ 0.96) indicate highly efficient Li⁺-dominated transport. Mechanical properties exhibit a trade-off between flexibility (elongation up to ~699%) and tensile strength (up to ~12.84 MPa), depending on the balance between plasticization and cross-linking. The degradation temperature is also strongly influenced by system composition, reaching ~508 °C in ionic liquid-modified systems. Overall, the performance of CMC-based SPEs is governed by the interplay between salt chemistry, polymer structure, and additive functionality. This review highlights key structure–property relationships and identifies critical research gaps, including salt-concentration optimization, long-term stability, and scalability, providing strategic insights for the rational design of high-performance, sustainable polymer electrolytes for next-generation energy storage applications. Full article

Given the widespread contamination of water bodies by diverse pollutants, particularly heavy metal ions and organic dyes, there is an urgent need to develop efficient and sustainable biomass adsorbents. Lignin is rich in active groups such as phenolic hydroxyl and carboxyl groups, making it a natural adsorbent. However, its application is still hindered by limitations, including restricted solubility and low reactivity. Converting lignin into three-dimensional porous hydrogels not only overcomes the inherent structural brittleness of lignin-based materials but also accelerates the diffusion kinetics of pollutants through well-developed pore structures, thereby fully exposing the active adsorption sites. This paper systematically reviews the latest progress in lignin-based hydrogels for water treatment and discusses in depth the underlying logic of “structure construction–micromorphology–adsorption performance.” First, this review summarizes synthesis strategies ranging from molecular-level modification to morphology regulation, including nano-reinforcement, magnetic functionalization, and interpenetrating polymer networks. It then provides a pollutant-specific analysis of the adsorption mechanisms of lignin-based adsorbents. For heavy metal ions, such as Pb²⁺ and Cr(VI), removal is mainly associated with coordination/complexation, ion exchange, and redox reactions. For typical organic dyes, adsorption is primarily driven by π–π interactions, hydrogen bonding, and electrostatic attraction. The effects of environmental factors, such as pH, are also systematically discussed. Finally, considering current challenges related to mechanical strength, regeneration performance, and practical application, this review outlines future research directions for the development of multifunctional, integrated, and stimuli-responsive lignin-based adsorbents. Full article

The premature deterioration of reinforced concrete structures caused by steel reinforcement corrosion remains a major challenge to long-term structural durability. This study systematically investigates the effects of corrosion inhibitor dosage on the fresh properties, mechanical performance, chloride ion penetration resistance, and capillary water absorption of self-compacting concrete (SCC). The evolution of the pore structure is characterized using low-field nuclear magnetic resonance (LF-NMR) and X-ray computed tomography (X-CT), and the proportions of pores within different equivalent spherical diameter ranges are quantified. In addition, the microstructural characteristics are examined by scanning electron microscopy (SEM). The results show that the incorporation of the corrosion inhibitor increases the viscosity of fresh SCC, resulting in reductions in slump. In general, the corrosion inhibitor reduces both the compressive strength and splitting tensile strength of SCC, with the smallest strength reduction observed at a corrosion inhibitor dosage of 2 wt%. All mixtures containing the corrosion inhibitor exhibit lower electric flux and water absorption than the control mixture, indicating improved resistance to chloride ion penetration and capillary water ingress. The combined LF-NMR, X-CT, and SEM results indicate that an appropriate corrosion inhibitor dosage may optimize the spatial distribution of hydration products, refine the pore structure, reduce total porosity, and suppress the formation of macropores. Overall, a dosage of 2 wt% provides the most favorable balance among workability, mechanical properties, durability, and microstructural compactness. These findings provide experimental support and technical guidance for the mixture design of durable SCC used in aggressive environments, including marine and salt-lake regions. Full article

Vitamin D comprises a group of fat-soluble secosteroids traditionally associated with animal physiology, calcium-phosphate homeostasis, and skeletal metabolism. However, vitamin D and related compounds have also been reported in taxonomically distinct non-animal systems, including fungi, microalgae, other algae, phytoplankton, and higher plants, although the strength of evidence differs substantially among these groups. This review synthesizes current knowledge on the occurrence, structural chemistry, UV-B-driven photochemical mechanisms, environmental determinants, analytical challenges, and biofortification potential of vitamin D formation in photosynthetic organisms and fungi. Vitamin D synthesis is initiated by UV-B radiation, primarily within the 290–315 nm range, which converts sterol precursors such as 7-dehydrocholesterol and ergosterol into previtamin D intermediates and is followed by thermal isomerization to the corresponding vitamin D forms. Continued irradiation may additionally generate lumisterol, tachysterol, and other photoproducts, thereby limiting net vitamin D accumulation. This non-enzymatic mechanism supports the interpretation that vitamin D formation can occur outside vertebrates when an appropriate 5,7-diene sterol precursor is accessible to a sufficient UV-B dose. In photosynthetic organisms and fungal matrices, net vitamin D accumulation is constrained by the spectral dose of UV-B, environmental exposure, tissue architecture, sterol localization, oxygen availability, antioxidant capacity, and ROS-mediated degradation. Studies of microalgae and phytoplankton, including reports concerning Emiliania huxleyi, suggest the occurrence or UV-B-dependent formation of both vitamin D₂ and vitamin D₃. However, these findings require evaluation according to the analytical method, use of authentic standards, experimental conditions, and confidence of compound identification. In fungi, the UV-B-induced conversion of abundant ergosterol to vitamin D₂ is well established. Microalgae represent a developing source of vitamin D₂ and vitamin D₃, whereas evidence for nutritionally relevant vitamin D accumulation in higher plants remains limited and heterogeneous. Although higher plants contain diverse phytosterols, the formation of vitamin D₄, vitamin D₅, or related analogues requires appropriate photoreactive 5,7-diene precursors and should not be inferred directly from the presence of common phytosterols such as β-sitosterol. Analytical detection remains challenging because of low concentrations, complex lipophilic matrices, and structural similarity among secosteroids and photoproducts; therefore, reliable identification requires validated analytical procedures. LC-MS/MS provides high sensitivity and selectivity but should be supported by authentic standards, preferably isotope-labelled internal standards, retention-time agreement, quantitative and qualifying ions, matrix-recovery assessment, limits of detection and quantification, and evaluation of ion suppression. Structurally similar analogues and photoproducts may additionally require orthogonal confirmation. Nutritionally, post-harvest UV-B enrichment of edible mushrooms is currently the best-validated strategy for increasing non-animal vitamin D₂ content. Microalgae constitute a developing platform for vitamin D₂ and vitamin D₃ production, whereas biofortification of higher plants remains experimental. Full article

Lead (Pb²⁺) pollution poses a severe threat to the ecological environment and human health due to its high toxicity, bioaccumulation, and refractory nature. Traditional treatment technologies for lead-contaminated wastewater, such as chemical precipitation, ion exchange, and membrane separation, often face limitations, including secondary pollution, high costs, and high energy consumption. In contrast, adsorption has emerged as a promising alternative technology with advantages such as a simple process, high efficiency at low concentrations, and renewability. Biomass-based hydrogels and their composite systems, as novel green adsorbent materials, combine the abundant functional groups of natural biomass with the structural stability, high porosity, and recoverability of hydrogels through a three-dimensional cross-linked network, offering unique advantages for lead ion adsorption. Depending on their composition, these systems range from fully biodegradable pure biopolymer networks to partly biodegradable or biomass-containing composites incorporating inorganic, carbon-based, or metal–organic framework (MOF) materials. This paper systematically reviews the latest research progress on cellulose, lignin, sodium alginate, chitosan, starch-based hydrogels, and their composite systems for lead (Pb²⁺) adsorption. First, the structural characteristics, cross-linking mechanisms, and functional modification strategies of various biomass hydrogels are introduced. Then, the adsorption mechanisms of Pb²⁺, including multiple modes of action such as coordination complexation, ion exchange, electrostatic interaction, and physical adsorption, are systematically analyzed. The adsorption performance of different material systems is compared in detail. The regeneration and recycling performance, as well as the potential practical applications, of the materials are evaluated. On this basis, the main challenges in current research are summarised: balancing adsorption capacity and mechanical strength, achieving selective adsorption in actual wastewater, improving regeneration efficiency, and optimizing costs. In addition, future development directions for biomass hydrogel adsorbent materials are discussed, including the design of multi-functional composite materials, the development of intelligent, responsive hydrogels, engineering-scale-up, and life-cycle assessment. This review aims to provide a theoretical framework and technical roadmap for the rational design of high-performance, sustainable hydrogel adsorbents and to promote their engineering application for the treatment of lead-contaminated wastewater. Full article

Hard carbon (HC) is one of the most promising anode materials for sodium-ion batteries (SIBs). Yet its sodiation mechanism—particularly the origin of the sloping and plateau regions in the voltage–capacity curve—remains debated. In this work, first-principles density functional theory (DFT) calculations are employed to systematically investigate the sodium storage mechanism at the edges and within the interlayer ultramicropores of bilayer graphene nanoribbons (BGNRs) with zigzag (BGNRs-Z) and armchair (BGNRs-A) terminations. A series of edge models, including hydrogenated, dehydrogenated (dangling bond), monovacancy (MV), and divacancy (DV) defects, were constructed to elucidate the effects of edge type and defect species on Na adsorption and intercalation. Our results demonstrate that Na ions preferentially adsorb at the edges rather than in the interior interlayer regions. The zigzag edge exhibits stronger binding affinity toward Na than the armchair edge. Progressive Na intercalation gradually opens the edge interlayer spacing. It reduces the interlayer angle toward a parallel configuration and accompanies a stacking transition from AB to AA at higher Na concentrations. Edge dangling bonds significantly enhance Na binding and drive the initial separation of edge carbon layers, whereas surface MV and DV defects contribute to Na adsorption at lower binding strengths. The calculated voltage–capacity relationships reveal that the first sloping region (>1.0 V) is primarily associated with Na adsorption at zigzag and defective edges, the second sloping region (0.1–1.0 V) can be rationalized by combined surface defect adsorption and interlayer intercalation, and the low-voltage plateau (<0.1 V) is thermodynamically linked to Na filling of narrow slit pores with optimized interlayer distances (~4.0 Å for zigzag and ~4.3–5.8 Å for armchair edges). These findings establish a direct structure–property correlation between carbon microstructure (edge type, defect architecture, and pore geometry) and the electrochemical voltage profile, offering atomic-level insights for the rational design of high-performance carbon-based anodes for SIBs. Full article

We give a systematic account of the soft mode dynamics of QCD critical point and the two-flavor color superconductivity based on the two-flavor Nambu–Jona-Lasinio model and investigate their effects on electromagnetic observables in relativistic heavy-ion collisions (HICs). We first demonstrate that the collective excitations coupled to the fluctuations of the respective order parameters are the soft modes associated with the phase transitions, in the sense that they acquire a prominent spectral strength in the low-energy and low-momentum region near the phase transitions, and the peak energy goes down, i.e., becomes softened and eventually vanishes at the critical point. It is shown that the diquark soft mode of the 2SC gives rise to the pseudogap, i.e., a depression in the density of states of the quark spectra around the Fermi surface above but in the vicinity of the critical temperature. Then, exploiting the ideas that were developed in condensed matter physics for describing the ‘para-conductivity’ in the normal phase of metal superconductors, we show that the soft modes cause an anomalous enhancement of electric conductivity and the dilepton production rate and discuss their relevance to HICs. Full article

Ordinary Portland cement (OPC) production contributes approximately 7–8% of global anthropogenic CO₂ emissions, driving urgent demand for clinker-efficient binders utilizing industrial by-products. Flue gas desulfurization (FGD) gypsum and ground granulated blast-furnace slag (GGBFS) represent underutilized industrial by-products with documented potential as supplementary cementitious materials. This study investigates the mechanical, durability and microstructural performance of OPC–GGBFS–FGD gypsum ternary concrete mixtures incorporating untreated flue gas desulfurization (FGD) gypsum at 0–20% of total binder mass and ground granulated blast-furnace slag (GGBFS) at 25–50% of total binder mass in M30 structural concrete (w/b = 0.45). Compressive, split tensile and flexural strengths were evaluated at 7–90 days alongside rapid chloride penetration (RCPT), water absorption, strength efficiency index (SEI) and SEM–EDX analyses. Binary GGBFS replacement progressively enhanced long-term compressive strength, with T35F0 attaining 55.6 N/mm² at 90 days (+33.7% relative to the OPC control). Moderate FGD gypsum contents (5–10%) further enhanced overall performance. Among all mixtures, T50F10 exhibited the best overall performance on the mechanical and durability indicators evaluated, achieving 54.2 N/mm² compressive strength at 90 days together with a rapid chloride permeability value of 410 C, corresponding to ‘Very Low’ chloride ion penetrability. Beyond 10% FGD gypsum, progressive multi-parameter deterioration was observed, and mixtures containing 20% FGD gypsum failed to meet the M30 design requirement at 28 days. SEM–EDX confirmed that optimum sulfate activation produced a dense C–(A)–S–H-rich matrix, while excess sulfate caused matrix disruption. The findings establish 10% FGD gypsum by total binder mass as the optimum sulfate activation threshold for the investigated GGBFS and FGD gypsum sources at w/b = 0.45, and demonstrate the potential of untreated industrial FGD gypsum to produce durable, low-clinker structural concrete. Full article