Radiocesium is an especially difficult analytical target because cesium-137 has a half-life of 30.2 years and cesium-134 has a half-life of 2.06 years, yet both can occur at extremely low concentrations in seawater. Major sources include fallout from atmospheric nuclear weapons tests, accidental releases such as Chernobyl and Fukushima, and authorized discharges from nuclear-fuel reprocessing plants. Before Fukushima, the review estimates that global fallout, local fallout and reprocessing discharges contributed approximately 69%, 24% and 7%, respectively, of global cesium-137 inputs. The 2011 Fukushima accident released about 19–25 petabecquerels of cesium-137, with approximately 15–20 petabecquerels entering the ocean. Detection therefore depends on concentrating cesium from tens or even thousands of litres of seawater into a compact medium that can be measured reliably.

Ammonium phosphomolybdate, or AMP, remains one of the two established analytical workhorses. It is a heteropolyacid salt built around a negatively charged Keggin framework, commonly written as (NH4)3PMo12O40·nH2O, whose interstitial ammonium ions can exchange with dissolved Cs+. The large, weakly hydrated Cs+ ion preferentially occupies bridging oxygen sites in the framework, allowing the exchange of Cs+ for NH4+ even in acidic media. A silica-based AMP exchanger has adsorbed cesium across nitric acid concentrations of 0.001–3 mol L−1. Conventional AMP coprecipitation is mature and permits chemical-recovery correction: reported precipitate yields for 20-litre seawater tests exceeded 97%, and radiochemical yields of 96.1–100.1% were obtained in separate 137Cs-spiked 5-litre samples. Its main burdens are transportation of large water volumes, acidification, bulky containers, slow settling, filtration and approximately a week of pretreatment.

Immobilizing AMP in polyacrylonitrile, or PAN, converts the fragile powder into a usable column medium. One Fukushima seawater study used 5 mL of AMP–PAN resin to process 20 litres at 35–40 mL min−1 and reported chemical recovery of 93.5% ± 5% across 55 samples; direct gamma spectrometry then reduced processing from several days to several hours. A 25 mL column processed about 100 litres at 240–320 mL min−1 in roughly six hours, but its six recoveries averaged 88.1% ± 3.3% and fell as flow increased. These results illustrate the central compromise: faster columns increase throughput but reduce contact time and recovery, while specialized resin remains comparatively expensive. Composite AMP systems—including granular and mesoporous forms, magnetic particles and graphene-oxide membranes—are promising, but most have not yet been systematically validated for trace radiocesium in large volumes of low-activity natural seawater.

Ferrocyanides offer the other established route. Copper ferrocyanide and potassium nickel hexacyanoferrate contain negatively charged Prussian-blue-type frameworks whose interstitial sodium or potassium can be replaced by Cs+. The ion sheds part of its hydration shell to enter the structure, where the framework charge, cyanide-bridge environment and exchange sites stabilize it. Copper ferrocyanide cartridges can enrich seawater in the field: a paired system processed 800–5,000 litres at 4–6 L min−1, and the activity ratio in the second cartridge was used to detect breakthrough. The recommended ratio was below roughly 0.2–0.3 for about 1,000 litres and 5 g of adsorbent; ratios reached 0.5–0.8 near 2,000 litres and 0.6–0.9 in five of six samples at 4,000–5,000 litres, making correction increasingly unreliable. Later nonwoven cartridges could be counted directly: 20 litres at 0.5 L min−1 took 40 minutes, with field recovery above 93%, although raising the flow to 2.5 L min−1 lowered recovery to 84–86%.

For accident-contaminated water, zeolites have the advantage of an established engineering role, relatively low raw-material cost and a framework that can exchange Cs+ with sodium, potassium, calcium and other cations. Following Fukushima, herschelite-packed KURION columns provided principal upstream cesium removal, while the parallel SARRY system used IONSIV IE-96 chabazite followed by IE-911 crystalline silicotitanate. Their advantages come with a major constraint: sea salts compete strongly for the same exchange sites. The capacity of KURION herschelite in 3.4 wt% sea-salt solution was approximately one-tenth of its capacity in pure water, and salinity also reduced the effective volume treated by a dynamic bed. Low-silica Na-CHA has separately removed more than 99% of ppt-level cesium-137 in actual nuclear-power-plant wastewater, but such treatment evidence does not establish the material as a principal tracer for quantitative seawater analysis.

Crystalline silicotitanates and layered titanates are tailored more explicitly to high-loading treatment streams. In H-CST, Cs+ enters eight-membered-ring channels and replaces H+, with local oxygen coordination helping stabilize the exchanged structure. Layered titanates instead exchange sodium, potassium or hydrogen from interlayers, while surface hydroxyls and sheet edges may also participate. TAM-5 separated ppm-level Cs+ at pH above 14 and sodium concentrations above 5 mol L−1. H-CTO nanosheets reached a reported maximum capacity of 329 mg g−1 and could be regenerated with 0.2 mol L−1 HCl, while a hydrophilic HTO-3 material reached 360 mg g−1 and equilibrium in about two hours. Titanium-based ion sieves and electrically controlled titanosilicate electrodes offer still more specialized routes, including preselected binding sites and potential-controlled intercalation and release, but many nanstructured forms remain difficult to shape and recover.

Metal sulfides and ion-imprinted materials provide another route to selective capture in hostile matrices. Layered sulfides combine exchange of interlayer cations with strong Cs···S interactions at polarizable sulfur sites. The layered Ti/Sn material KTSS reached equilibrium in about one minute and had a maximum capacity of 450.12 mg g−1. FJSM-KCGTS was built with Cs+ as a template, activated with K+ after template removal, and retained more than 99% removal in actual industrial wastewater containing 137Cs; its capacity in spiked seawater was 206.44 mg g−1. It also retained more than 99.5% removal after 100 or 200 kGy gamma irradiation and more than 98.97% after three regenerations with 1 mol L−1 ammonium chloride. These are encouraging treatment results, but most seawater experiments used elevated stable-Cs spikes and therefore do not demonstrate quantitative recovery of trace 137Cs from natural seawater.

The frontier in analytical enrichment is increasingly molecular. Metal-organic frameworks can bind Cs+ through framework counterions, sulfonic or carboxylic groups, and crown-ether cavities that mimic the ion’s preferred coordination environment. ZJU-X102 incorporates a 24-crown-8 unit and has a reported maximum capacity of 121 mg g−1, while an anionic indium-based layered framework reached 297.67 mg g−1 and a cesium/strontium separation factor of about 320. An NH2-MIL-125(Ti)@ZIF-8 heterostructure reported 392.62 mg g−1 capacity by adding interfacial sites. Immobilized macrocycles are more selective still: a calixarene resin had a Cs+ selectivity coefficient above 300 in nitric-acid feed and retained performance after 500 kGy irradiation. Their narrow recognition cavities suit small-volume enrichment or fine separation, but costly synthesis, ligand loss, salt tolerance and competition from potassium limit seawater use.

The review’s practical conclusion is that no material yet wins every category. AMP and ferrocyanide systems have the clearest foundation for quantitative seawater analysis, yet acidification, column breakthrough, flow sensitivity and cost remain important limitations. Zeolites and crystalline silicotitanates have demonstrated fixed-bed treatment of accident-contaminated water, but seawater salts reduce uptake and effective bed volume. Emerging materials should therefore be judged by the application they are intended to serve. Analytical candidates need validation in low-activity natural seawater for overall recovery, blanks, usable flow rates and maximum treatable volume. Treatment candidates require dynamic breakthrough, service life, radiation stability, leaching and safe immobilization data. Cold-sintered Cs-AMP and thermally converted Cs-zeolite also show how adsorption can be linked to waste-volume reduction and final disposal, but no laboratory capacity result or stable-Cs spike substitutes for sustained, trace-level field validation.

Subject of Research: Materials for enriching radioactive cesium isotopes from seawater and treating nuclear-polluted water

Article Title: Materials used for enriching radioactive cesium isotopes from seawater

Article References: Ling, C., Qian, S., Zhang, K., Zhu, S., Gu, Y., Ma, Z., & Ren, Y. (2026). Materials used for enriching radioactive cesium isotopes from seawater. Frontiers in Marine Science, 13, Article 1996662. https://doi.org/10.3389/fmars.2026.1996662

Image Credits: AI Generated

DOI: 10.3389/fmars.2026.1996662

Keywords: radiocesium, cesium enrichment, seawater analysis, nuclear wastewater, adsorption materials, ammonium phosphomolybdate, ferrocyanides, zeolites, metal-organic frameworks, water treatment, Materials, used

General surgery presents an unusually demanding combination of biological and mechanical hazards. Blood can dilute uncured polymers or obscure reactive groups, while mucus, intestinal contents, bile, pancreatic enzymes and polymicrobial biofilms interfere with bonding or tissue integration. At the same time, abdominal-wall implants face repeated multidirectional loading, anastomotic coatings must tolerate transient pressure without narrowing the lumen, and liver patches must stop diffuse bleeding on soft parenchyma without obstructing drainage. The review therefore treats time as a design variable: mixing, curing and hemostasis occur within minutes; leakage resistance and microbial control unfold over hours and days; collagen deposition, vascularization and remesothelialization extend across weeks; and mesh contraction, degradation and chronic foreign-body responses become important months later.

Hydrogels are among the most flexible platforms because their water-rich networks conform to tissue and can carry drugs, peptides, extracellular matrix or cells. Natural materials including gelatin, collagen, fibrin, hyaluronic acid, alginate, chitosan and decellularized matrix provide biological cues, while synthetic polymers permit tighter control of mechanics and manufacturing. Hybrid and double-network formulations combine covalent crosslinks, reversible bonds, supramolecular interactions or nanofillers to improve strength and healing performance. Stimuli-responsive variants can gel with temperature, change with pH or enzyme exposure, release antimicrobial or antitumor agents in pathological environments, or self-heal after deformation. The critical trade-off is that a formulation optimized for stiffness may be unusable if it cures too slowly, swells excessively, loses adhesion in blood or degrades outside the operative window.

Clinical and preclinical comparisons illustrate why surgical context can reverse apparent performance. A 2022 meta-analysis of 15 studies, involving 1,387 patients with coated intestinal anastomoses and 2,243 controls, associated collagen-based laminar materials or fibrin sealants with lower leakage, fewer reoperations and fewer major complications. Hospital stay was also shorter by a weighted mean of 1.96 days, although heterogeneity for that outcome was high. Material-level experiments are less consistent: in a mouse partial-cecal-transection model, a solution blow-spun polymer produced a mean 24-hour burst pressure of 81.0 ± 20.3 mmHg, compared with 5.7 ± 5.0 mmHg for fibrin glue and 10.2 ± 2.5 mmHg for polyethylene glycol hydrogel. But a four-piglet study found that adding the same spun polymer raised immediate burst pressure from 10.9 ± 9.0 to 36.5 ± 4.6 mmHg without statistical significance, and all animals survived 14 days without leakage.

The models can also show that more reinforcement is not always better. In rats whose ascending-colon anastomoses were tested on postoperative day 7, controls burst at 221 ± 19.41 mmHg, compared with 151 ± 14.42 mmHg after a collagen-fibrinogen patch and 112 ± 13.57 mmHg after fibrin glue. Histological healing did not differ among the analyzed groups, suggesting that a material capable of bridging a major early defect may constrain later remodeling or concentrate stress at its edge. Variables such as anastomotic location, perfusion, defect severity, bacterial exposure, inflation rate, bowel diameter and testing time all influence measured burst pressure. The review consequently argues that sealants should be evaluated immediately and during the postoperative interval when collagen remodeling makes the tissue vulnerable, with stenosis, obstruction, abscess and mortality reported alongside leakage.

For abdominal-wall reconstruction, additive manufacturing offers control over pore architecture, fiber direction, thickness and material gradients that a conventional mesh cannot easily provide. A rapamycin-loaded liposome and polyvinyl alcohol coating reduced the mean 30-day adhesion score from 3.00 ± 0.71 for unmodified polypropylene to 1.37 ± 0.75 in one implantation study, while a separate mussel-inspired coating reduced adhesion area and tenacity by more than 80% relative to native polypropylene in rats. These are different endpoints from different models, however, and neither establishes protection against human hernia recurrence. More elaborate Janus implants place a smooth, antifouling face toward bowel and a porous face toward tissue that must undergo fibrovascular ingrowth. One peritoneum-inspired hydrogel had a maximum swelling ratio of 6.4% and retained strength after 14 days in phosphate-buffered saline, illustrating why surface asymmetry can matter more than a single bulk modulus.

Additive manufacturing can also separate opposing functions, but it introduces manufacturing and regulatory complexity. Extrusion printing accommodates viscous and cell-laden inks but can expose cells to nozzle shear; light-based printing provides finer resolution but requires control of photoinitiator exposure and optical dose; melt printing creates stronger polymer structures but is less compatible with living components. Decellularized extracellular-matrix bioinks retain tissue-associated proteins and glycosaminoglycans, yet donor variation, residual DNA, sterilization, batch consistency and weak mechanics complicate scale-up. In hepatobiliary surgery, one multicenter randomized trial of 50 patients found a median hemostasis time of 1.0 minute for an oxidized-cellulose patch with self-adhesive hydrogel components, versus 3.0 minutes for a fibrin-sealant patch. Because the comparator required a three-minute application, the difference reflected workflow as well as chemistry, illustrating the need to measure how a material fits into surgical practice.

Smart materials are also being developed for postoperative tumor beds, where injectable hydrogels can fill irregular spaces and retain chemotherapy, immune stimulators or photothermal agents near residual disease. A dopamine-functionalized dual-crosslinked hyaluronic-acid sealant adhered to a pancreatic stump, limited postoperative amylase and lipase elevation and delivered interleukin-15 plus anti-TIGIT-functionalized platelets in murine pancreatic-cancer models. Such combinations also make interpretation harder: tumor response, immune-cell distribution, wound healing, infection, anastomotic integrity and systemic exposure must be separated, and a local therapy cannot be considered successful if it compromises fascial or gastrointestinal healing. Artificial intelligence may eventually help select formulations, but current evidence is much narrower. A random-forest model predicted bioink viscosity with an R-squared value of 0.99 from 169 measurements, yet the random train-validation split did not test new polymer batches, printers or laboratories, and viscosity is not equivalent to print fidelity or clinical performance.

To address these gaps, the authors propose a six-stage GS0–GS5 hierarchy designed to complement, rather than replace, general technology-readiness and regulatory systems. GS0 defines the clinical use case and material hypothesis; GS1 establishes bench performance such as gelation, swelling, wet adhesion, degradation and cytocompatibility; GS2 tests the material against relevant blood, bile, enzymes, biofilm, cyclic loading, surgical delivery and rescue conditions. GS3 requires randomized and, where feasible, blinded small-animal disease models with safety and mechanistic endpoints. GS4 tests handling, fixation, drainage, durability and follow-up in anatomically scaled models, while GS5 covers manufacturing, sterilization, packaging, surgeon training and early clinical feasibility. Because conditions differ by operation, a material validated for skin closure would not automatically qualify for a pancreatic stump.

The review identifies immediate research priorities that reflect the limits of the evidence: fatigue-tested asymmetric abdominal-wall constructs, laparoscopically deliverable anti-adhesion barriers, standardized anastomotic models with immediate and delayed burst testing, and sealants exposed to bile or pancreatic enzymes. Patient-derived liver, pancreatic and tumor models should be judged by prospective predictive performance rather than descriptive biomarkers alone. Across all these applications, advancement should depend on meaningful surgical endpoints, transparent reporting and manufacturability, not chemical novelty alone. The review itself used a targeted PubMed search updated through July 2026 and 107 verified records, but it was not a systematic review, carried no registered protocol or formal risk-of-bias assessment, and therefore offers design guidance rather than pooled efficacy estimates.

Subject of Research: A narrative review of smart materials, additive manufacturing and staged validation for general-surgical reconstruction.

Article Title: Smart materials and additive manufacturing for functional reconstruction in general surgery: responsive hydrogels, bioinks, patient-specific scaffolds, and translational validation

Article References: Lou, Y., He, R., Liu, X., & Wang, H. (2026). Smart materials and additive manufacturing for functional reconstruction in general surgery: responsive hydrogels, bioinks, patient-specific scaffolds, and translational validation. Frontiers in Bioengineering and Biotechnology, 14, Article 1977492. https://doi.org/10.3389/fbioe.2026.1977492

Image Credits: AI Generated

DOI: 10.3389/fbioe.2026.1977492

Keywords: smart materials, responsive hydrogels, additive manufacturing, surgical reconstruction, bioinks, patient-specific scaffolds, hernia repair, anastomotic sealing, surgical biomaterials, translational validation, Smart, materials

The two species at the heart of the study are Glycyrrhiza uralensis Fisch. and Glycyrrhiza inflata Bat., which together account for more than 85 percent of the medicinal licorice circulating in the Chinese market. Both are official botanical origins of Gan Cao, but their chemical profiles differ in ways that matter for efficacy and clinical safety. Traditional authentication relies on morphological and microscopic features such as cork cell arrangement, fiber bundle compactness, and the abundance of calcium oxalate crystals. These characteristics overlap heavily between the two species, and judgments depend on the subjective experience of the identifier. Molecular methods based on chloroplast DNA markers can discriminate the species, but they typically require fresh samples and are too cumbersome for the high-throughput demands of commercial quality control.

The researchers’ solution starts with a deceptively simple observation: even when licorice samples differ in geographical source, growth years, or harvest batch, material from the same species inevitably contains the same core chemical components. The team analyzed 35 batches of G. uralensis and 35 batches of G. inflata, all botanically verified against the 2025 Chinese Pharmacopoeia, using a Waters QTOF high-resolution mass spectrometer. Samples were ground, sieved, and extracted with 75 percent methanol under ultrasonication, then separated on a UHPLC C18 column with a 45-minute gradient elution. Detection ran in both positive and negative electrospray ionization modes, scanning masses from 50 to 1200 daltons. The raw data were converted into a three-dimensional matrix of retention time, mass-to-charge ratio, and ion intensity, yielding between roughly 4,000 and 9,500 ion features per batch.

From this torrent of data, the researchers constructed two complementary matrices. The first, the common ion matrix, or CIM, captures the twenty most intense ions that recur consistently across every batch of a species, regardless of origin, growth year, or storage conditions. These ions represent the stable chemical backbone shared by all genuine samples of that species. The second, the exclusive ion matrix, or EIM, is built by removing the ions that the two species share and retaining the twenty most intense species-specific features. The distinction matters because the two licorice species are chemically close cousins: their total ion chromatograms look strikingly similar, and both contain compounds such as liquiritigenin and liquiritin at nearly identical retention times and masses.

That chemical kinship became obvious in the first round of matching. When test samples were compared against the common ion matrices, every G. uralensis sample scored a matching confidence of at least 90 percent against its own species matrix, but it also scored 60 to 90 percent against the G. inflata matrix. The confidence increment rate, a novel parameter the team devised to express how much better a sample matches one species than the other, ranged only from 0.06 to 0.58. In other words, the common ion matrix alone could provide a preliminary screening but could not deliver unambiguous discrimination. The researchers therefore designed a hierarchical matching strategy in which the CIM serves as the first gate, requiring a matching confidence of at least 90 percent, before the sample proceeds to the decisive second stage.

The second stage, based on the exclusive ion matrices, proved dramatically more selective. G. uralensis samples scored 80 to 100 percent against their own exclusive matrix while dropping to zero or 5 percent against the G. inflata matrix, with confidence increment rates exceeding 17. G. inflata samples scored at least 70 percent against their own exclusive matrix and no more than 10 percent against the foreign one. Through cutoff optimization across an external validation set of 30 batches, the team established a dual criterion: a sample is authenticated only if its matching confidence reaches at least 70 percent and its confidence increment rate reaches at least 6.00, applied as a logical AND. Receiver operating characteristic analysis of this combined model returned an area under the curve of 1.00, with 100 percent sensitivity and 100 percent specificity and no false positives or false negatives.

The method’s practical power was demonstrated on ten batches of commercial licorice purchased blind from the market. Eight batches were authenticated as G. uralensis and two as G. inflata, with the market samples showing matching confidences of at least 70 percent against their own exclusive matrices and confidence increment rates of 12 or higher. Method validation confirmed the analytical foundation: mass errors stayed within 5 parts per million, precision relative standard deviations remained below 0.14 percent, and repeatability and stability deviations stayed below 0.70 percent over 48 hours. The blank solvent produced no significant interference, confirming the method’s specificity.

Chemometric analysis added a second layer of evidence. Using UPLC-QTOF-MS data from 20 batches of each species, the researchers applied principal component analysis and orthogonal partial least squares discriminant analysis, which cleanly separated the two species with an R2Y of 0.989 and a Q2 of 0.992. A permutation test and CV-ANOVA confirmed the model was valid and not overfitted. Screening markers with a variable importance in projection threshold of 10.0 revealed seven differential chemical markers. For G. inflata, the markers were licochalcone A, licochalcone B, echinatin, and glabrol, with VIP values up to 25.01. For G. uralensis, the markers were licoricidin, licoricone, and glycycoumarin. Ion distribution profiles showed these compounds were prominent in one species and nearly absent in the other, consistent with earlier reports in the literature.

The deeper significance of the work lies in its conceptual shift. TCM-ID moves authentication away from the structural elucidation of individual marker compounds and toward the digital quantitative characterization of the entire chemical profile, making full use of massive datasets that include thousands of unidentified components. Because the common ion matrix absorbs the natural variability caused by cultivation region, growth years, and harvest batch, while the exclusive ion matrix captures the interspecific differences, the combined criteria avoid the limitations of single-index identification. The researchers note that the same strategy has already been applied to angelica, saposhnikovia, and bile powder, suggesting a generalizable framework for botanical origin traceability across many traditional medicines.

Limitations remain. The study focused only on G. uralensis and G. inflata, excluding Glycyrrhiza glabra, the third official licorice species, so the current cutoff values apply only to the two species examined. The team plans to add G. glabra specimens and multi-batch data to optimize the matrices and thresholds for comprehensive three-species identification. Still, the methodological framework is highly replicable, and the authors argue that TCM-ID offers a promising route for origin traceability and quality evaluation of herbal medicines. As traditional Chinese medicine enters its digital and intelligent era, the licorice identity card may become a template for how regulators authenticate the botanical origins of the world’s herbal pharmacopoeia, one mass spectrum at a time.

Subject of Research: A novel digital identification strategy for licorice raw materials: TCM-ID with common/exclusive ion matrices and hierarchical matching

Article Title: A novel digital identification strategy for licorice raw materials: TCM-ID with common/exclusive ion matrices and hierarchical matching

Article References: Wang, X., Wu, Y., Wan, L., Zhang, J., He, F., Jing, W., Chen, J., Cheng, X., & Lin, Y. (2026). A novel digital identification strategy for licorice raw materials: TCM-ID with common/exclusive ion matrices and hierarchical matching. Frontiers in Chemistry, 14, Article 1918761. https://doi.org/10.3389/fchem.2026.1918761

Image Credits: AI Generated

DOI: 10.3389/fchem.2026.1918761

Keywords: novel, digital, identification, strategy, licorice, materials, TCM-ID, common, exclusive, matrices, hierarchical, matching

The problem the team set out to solve is structural. During years of charging and discharging, LFP cathodes lose lithium ions, and the crystal lattice degrades toward iron phosphate, which is electrochemically inert in this context. Conventional recycling approaches, whether pyrometallurgical smelting or hydrometallurgical acid leaching, are energy-hungry and often fail to restore the degraded cathode structure; they break the material down and rebuild it from scratch, consuming large amounts of heat, chemicals, and water. Direct regeneration, by contrast, aims to replenish the missing lithium and heal the lattice while keeping the original particle morphology intact, which preserves much of the embodied energy and manufacturing value of the cathode powder.

The Chinese team’s strategy is a low-dose MnO₂-assisted hydrothermal process. They used lithium phosphate (Li₃PO₄) as the lithium source, glucose as the reductant, and a small amount of manganese dioxide as a catalytic promoter. The spent cathode material is immersed in this reaction medium and treated hydrothermally, allowing lithium to re-enter the degraded lattice under relatively mild conditions. A subsequent annealing step completes the reconstruction of the olivine LFP structure. The choice of MnO₂ is intriguing because manganese dioxide is a well-known heterogeneous catalyst in fields ranging from air cathodes to ozonation and organic oxidation reactions, but its role in battery relithiation chemistry had not been explored in this way before.

The results are impressive for such a simple process. Under optimized conditions, the regenerated LFP achieved a Li/Fe molar ratio of 0.98, very close to the stoichiometric ideal of 1.0, indicating that lithium replenishment was nearly complete. The recovered material delivered a discharge capacity of 142.3 mAh g⁻¹ at 0.2 C, which approaches the theoretical capacity of LFP, and maintained stable cycling performance over 200 cycles at 0.2 C. Electrochemical impedance spectroscopy revealed a charge-transfer resistance of 87.35 Ω, suggesting that the regenerated cathode surface and particle interfaces were restored to a state that supports efficient lithium-ion transport and electron transfer during battery operation.

What makes the MnO₂ addition so effective? The authors describe its role as catalytic-promoting, based on combined structural, surface-chemical, and electrochemical evidence, although they candidly acknowledge that the detailed reaction pathway requires further investigation. One plausible picture is that MnO₂ participates in the redox chemistry of the hydrothermal system, facilitating the transfer of lithium from the Li₃PO₄ source into the iron phosphate framework while glucose serves as the reductant that maintains favorable oxidation states. Manganese dioxide is known to mediate electron transfer and oxygen-related redox reactions in aqueous environments, and similar mediation chemistry has been shown to enable low-temperature hydrothermal relithiation in other cathode recycling studies. The exact mechanism in this LFP system, however, remains an open question that the team flags for future work.

The significance of this approach becomes clear when compared with the broader landscape of LFP recycling. Recent reviews describe a spectrum of direct regeneration technologies, including solid-state annealing, molten salt relithiation, electrochemical relithiation, ultrasonic methods, and redox-mediated hydrothermal processes. Each has advantages and limitations in terms of temperature, processing time, chemical consumption, and scalability. The hydrothermal route is attractive because it operates at moderate temperatures and in an aqueous medium, avoiding the extreme heat of solid-state methods and the aggressive acids of leaching routes. The use of Li₃PO₄ as the lithium source is notable because it is a relatively benign, phosphate-based compound that matches the anion chemistry of the cathode itself, and glucose is an inexpensive, renewable reductant.

The environmental case for direct regeneration of LFP is compelling. LFP batteries contain no cobalt or nickel, so the traditional economic drivers for recycling are weak, and yet the volume of retiring LFP packs is enormous and growing. If degraded cathode powder can be repaired rather than broken down, the energy and chemical inputs per kilogram of recovered cathode drop substantially, and the carbon footprint of new battery production falls accordingly. Direct regeneration also avoids the generation of mixed metal sulfate streams and wastewater that characterize hydrometallurgical routes, and it preserves the particle morphology and carbon coating that manufacturers spent considerable effort optimizing in the first place.

Challenges remain before this chemistry can leave the laboratory. The study was conducted on spent cathode materials under controlled conditions, and real-world recycling streams contain impurities, mixed chemistries, aluminum and copper foils, electrolyte residues, and binder contaminants that complicate any regeneration process. The authors themselves note that the catalytic role of MnO₂, while supported by evidence, is not yet fully understood at the mechanistic level, and understanding it could unlock further improvements in efficiency and dose reduction. Scaling hydrothermal reactors to industrial throughput, ensuring uniform treatment of ton-scale cathode powder, and integrating the process with upstream sorting and downstream electrode fabrication are all engineering hurdles that must be addressed.

Nevertheless, the work adds an important piece to the puzzle of sustainable LFP recycling. It demonstrates that a catalytic promoter, even at low dose, can meaningfully enhance a direct regeneration process, and it provides a feasible route for restoring spent LFP cathode materials with performance approaching that of virgin material. As the volume of retiring LFP batteries from electric vehicles and energy storage systems continues to climb, approaches like this one, which repair rather than destroy, will be essential to closing the loop on battery materials. The vision of a circular battery economy, in which end-of-life packs become feedstock for new ones with minimal energy loss and environmental burden, moves one step closer with each such advance in direct regeneration chemistry.

Subject of Research: MnO₂-assisted hydrothermal regeneration of spent LiFePO₄ cathode materials for sustainable lithium-ion battery recyclingAuthors:

Article Title: MnO₂-assisted hydrothermal regeneration of spent LiFePO₄ cathode materials for sustainable lithium-ion battery recyclingAuthors:

Article References: Wu, Y., Chi, M., Bai, L., Tuo, J., Li, S., Song, X., Zhang, C., Qiao, J., Li, J., & Wang, B. (2026). MnO₂-assisted hydrothermal regeneration of spent LiFePO₄ cathode materials for sustainable lithium-ion battery recyclingAuthors:. Ionics. https://doi.org/10.1007/s11581-026-07584-y

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07584-y

Keywords: assisted, hydrothermal, regeneration, spent, LiFePO, cathode, materials, sustainable, lithium-ion, battery, recyclingAuthors, scientific research

The clinical burden underlying this research direction is substantial. Osteomyelitis, the infection of bone marrow and surrounding bone tissue addressed in the review, is driven most often by Gram-positive staphylococci, with Staphylococcus aureus alone implicated in roughly 44% to 75% of cases and particularly dominant in chronic presentations. Once established, these infections resist conventional treatment not simply because the bacteria themselves are hardy, but because they organize into biofilms—structured communities that adhere to implant surfaces, necrotic bone fragments, and other hospitable niches. Within these communities, bacteria are shielded from both innate and adaptive immune responses and display markedly reduced susceptibility to antimicrobial drugs. The result is a vicious cycle in which surgical debridement and prolonged antibiotic courses frequently fail to eradicate the infection, leaving many patients to progress to chronic disease marked by inflammation-driven bone destruction, heightened osteoclast activity, and secondary osteonecrosis.

The piezoelectric principle at the heart of the proposed strategy rests on a deceptively simple physical property. Materials with non-centrosymmetric crystal lattices—meaning their internal structure lacks a center of symmetry—develop separated positive and negative charge centers when mechanically deformed. This deformation generates electric dipoles and, on the material surface, localized bound charges. The phenomenon runs in both directions: the direct piezoelectric effect converts applied mechanical force into electrical charge, while the inverse effect converts an applied electric field into mechanical deformation. For biomedical purposes, the direct effect is the more relevant one, since it allows the body’s own mechanical environment—walking, loading, ultrasound applied from outside, even subtle internal tissue movements—to be harvested as a source of localized electrical stimulation without any external power supply implanted at the site.

What makes this particularly attractive for infected bone is the multiplicity of antibacterial mechanisms that can flow from that single physical event. When a piezoelectric surface is mechanically stimulated, the resulting charge separation can, in catalytically active systems, drive redox reactions that generate reactive oxygen species. These highly reactive molecules damage bacterial membranes, interfere with intracellular redox balance and respiratory processes, and attack the extracellular polymeric matrix that gives biofilms their structural integrity. Importantly, the review emphasizes that reactive oxygen species are not the whole story. Electrical perturbation at the material surface, direct mechanical disruption of biofilm architecture, interfacial electron transfer, and the release of metal ions can each contribute to bacterial killing and biofilm dismantling. This mechanistic plurality matters clinically, because a therapy that attacks bacteria through several parallel pathways is inherently less vulnerable to the resistance mechanisms that defeat single-target antibiotics.

The review’s authors argue that the field has tended to organize itself around material classifications, antibacterial mechanisms, or application categories, and that this taxonomy has obscured something clinically essential: bone infection is not a static problem but a dynamic pathological sequence. Persistent biofilms, dysregulated antimicrobial immunity, excessive or unresolved inflammation, and impaired angiogenesis and osteogenesis are not independent events. They are interconnected processes that unfold in a characteristic order as infection is controlled and repair proceeds. A material that aggressively generates reactive oxygen species may be ideal in the first days after debridement, when bacterial load and biofilm burden are highest, yet counterproductive weeks later, when the priority shifts to protecting nascent blood vessels and differentiating osteoblasts from oxidative damage.

To resolve this tension, the authors propose a stage-adaptive therapeutic framework. In the early infection-control phase, the priorities are biofilm disruption, bacterial eradication, and activation of antimicrobial immune functions. Piezoelectrically generated electrical signals and reactive oxygen species serve these goals directly, while the same stimuli can polarize immune cells toward a microbicidal phenotype that complements the materials’ direct antibacterial action. Once the infectious burden has been sufficiently reduced, the therapeutic emphasis must pivot: oxidative stress must now be contained, persistent inflammation resolved, and the immune microenvironment remodeled toward a pro-reparative state that supports angiogenesis—the sprouting of new blood vessels that supply regenerating tissue—followed by osteogenesis, the deposition of new bone matrix.

This reframing has practical consequences for material design. Rather than seeking a single material that maximizes every desirable property simultaneously, the framework suggests that next-generation implants might be engineered to modulate their own behavior over time, for example by tuning piezoelectric output, incorporating catalytic components whose activity is triggered by the local microenvironment, or layering coatings that release pro-regenerative signals only after the acute phase has passed. The review also situates piezoelectric materials within a broader lineage of biomedical applications; these substances already serve as nanogenerators in soft tissue repair and underpin technologies from medical ultrasound transducers to aerospace actuators and radio-frequency filters in consumer electronics, reflecting decades of industrial maturation that could accelerate clinical translation.

The immune dimension of the framework deserves particular attention, because it connects the antibacterial and regenerative phases into a coherent narrative. The review synthesizes evidence that piezoelectric stimulation can modulate the infection-associated immune microenvironment, steering the inflammatory response in ways that support both bacterial clearance and subsequent repair. This is a subtle balancing act. The same inflammatory programs that mobilize bactericidal activity early in infection can, if left unresolved, drive the bone destruction and fibrosis that characterize chronic osteomyelitis. A material platform that first amplifies antimicrobial immunity and then facilitates its resolution—without requiring drug interventions at each transition—would address one of the most persistent failures of current therapy, in which dysregulated host responses perpetuate disease even after bacteria have been substantially cleared.

The authors are candid about the obstacles that remain between this framework and routine clinical use. Material design optimization is an ongoing challenge: piezoelectric coefficients, biocompatibility, degradation behavior, and mechanical properties must be balanced within a single implantable system, and the optimal parameters likely differ between the infection-control and repair phases. Mechanistic understanding also remains incomplete. While the individual pathways—piezocatalytic reactive oxygen generation, electrical stimulation of cells, immune modulation—have each been demonstrated, their relative contributions in vivo, their interactions with one another, and their dependence on the local mechanical loading environment are not yet fully mapped. Clinical translation faces the additional hurdle that most supporting evidence comes from in vitro and preclinical models, which rarely reproduce the complexity of human osteomyelitis with its mixed bacterial populations, devitalized bone, and compromised vascularity.

Nevertheless, the conceptual contribution of the review lies in its insistence that therapeutic functions be evaluated against the pathophysiological timeline of the disease rather than in isolation. By integrating antibacterial action, immunomodulation, and regeneration into a single stage-adaptive sequence, it offers researchers a design logic: identify which phase of the disease a given material property serves, and engineer materials whose properties evolve in step with the patient’s needs. If that logic can be validated experimentally and carried through to clinical devices, piezoelectric biomaterials could shift the treatment of infected bone from a reactive cycle of debridement and antibiotics toward an active, self-regulating partnership between implant and host tissue—one in which the mechanical energy of everyday movement becomes a therapeutic resource deployed precisely when and where the healing process requires it.

Subject of Research: Piezoelectric biomaterials for treating bone infection through bacterial eradication, immune modulation, and bone regeneration

Article Title: Immunomodulation and biofilm disruption of piezoelectric materials in bone infection

Article References: Wang, Z., Zheng, K., Tang, Y., Zhang, Z., Zhong, Z., Wang, D., Chen, Z., Wang, Y., Chen, Z., Feng, P., Huang, W., Liu, M., Hao, Y., Yu, F., Wang, G., Yi, M., & Deng, X. (2026). Immunomodulation and biofilm disruption of piezoelectric materials in bone infection. Frontiers in Cell and Developmental Biology, 14, Article 1976300. https://doi.org/10.3389/fcell.2026.1976300

Image Credits: AI Generated

DOI: 10.3389/fcell.2026.1976300

Keywords: piezoelectric materials, bone infection, biofilm, osteomyelitis, reactive oxygen species, immunomodulation, bone regeneration, antibacterial biomaterials, disruption, piezoelectric, materials, bone

The research, led by Martina Mercurio and Concetta Rispoli of the University of Naples Federico II together with colleagues from several Italian institutions, took a fresh look at the pozzolana deposits of the Campi Flegrei, the volcanic district west of Naples. The team collected samples from historical quarries that the Romans themselves are known to have exploited, extending from Naples to Bacoli. One sample, labeled SAV, came from an ancient tuff quarry in Marano di Napoli and represents pozzolana in the strict sense, the unconsolidated facies of the Neapolitan Yellow Tuff. Two others, labeled CL and LP, were collected near Baia, close to the Pontile Lubrano, an area where Imperial-age ceramics and artifacts testify to intense Roman maritime activity. Crucially, these two deposits belong to eruptions that occurred after the Neapolitan Yellow Tuff event, within the caldera’s later Epoch II activity.

The geological setting explains why this region is so rich in reactive ash. The Campi Flegrei caldera took shape through two cataclysmic collapses: the Campanian Ignimbrite eruption about 40,000 years ago, which ejected between roughly 60 and 300 cubic kilometers of phonolitic-trachytic material and ranks as the largest eruption in the Mediterranean over the past 200,000 years, and the Neapolitan Yellow Tuff eruption about 15,000 years ago, which produced around 50 cubic kilometers. After that second caldera-forming event, more than 70 eruptions occurred within the caldera, grouped into three epochs, the most recent ending with the Monte Nuovo eruption in AD 1538. These later eruptions, mostly explosive events of intermediate to Plinian scale, scattered cones and ash deposits across the entire territory. The magmas are potassic-alkaline in character, dominated by trachytic and trachy-phonolitic compositions, with clinopyroxene, plagioclase, sanidine, biotite and magnetite as the principal mineral phases.

To determine whether these post-Neapolitan Yellow Tuff deposits could genuinely serve as hydraulic binders, the researchers deployed a battery of modern analytical techniques. Polarized optical microscopy revealed the texture of pumice fragments and their crystal cargo; X-ray powder diffraction identified the mineral assemblage, including the zeolites phillipsite and analcime that form when hot reactive glass interacts with hydromagmatic fluids; field-emission scanning electron microscopy coupled with energy-dispersive spectroscopy delivered precise chemical analyses of individual volcanic glass fragments; and X-ray fluorescence characterized the whole-rock composition. Laser particle-size analysis measured the grain-size distribution of the fine fractions, the portion Roman craftsmen would have crushed or selected deliberately, since finer particles expose more reactive surface area. The samples proved remarkably similar in texture and mineralogy, all containing fresh volcanic glass, pumice fragments with elongated vesicles, and the zeolitic association typical of Phlegraean pyroclastic products.

The chemistry told the most compelling story. On the standard Total Alkali versus Silica classification diagram, the whole-rock compositions of CL and LP plot as trachyte while SAV falls in the latite field. But the decisive evidence came from individual point analyses of the glass component itself, which bypasses the diluting influence of crystals, lithic fragments and alteration products. Glass from CL and LP overlaps the compositional fields of the Baia-Fondi di Baia eruption, a small multievent eruption that occurred 9,500 to 9,600 years ago on the western side of Pozzuoli, while SAV glass matches the Neapolitan Yellow Tuff field. The potassium-to-sodium ratio proved a particularly sharp discriminator: CL and LP glasses show ratios of two or higher, excluding the low-ratio Averno eruption, whereas SAV aligns with the Neapolitan Yellow Tuff. These geochemical attributions agree with the official geological cartography of the sampling sites.

The team then confronted their quarry samples with published glass analyses of pozzolanic aggregates extracted from actual Roman mortars across the Mediterranean. The dataset spanned local Campanian monuments, including the Baths of Baia, the Flavian Amphitheater of Pozzuoli and the vast Piscina Mirabilis cistern, as well as distal sites: Roman structures in the Venice Lagoon, the Roman theater of Aquileia in northeastern Italy and the ancient city of Hippo Regius in Algeria. The glass compositions from these mortars fall within the compositional range of the Neapolitan Yellow Tuff and, tellingly, match the variability of Baia-Fondi di Baia products as well. Some anomalies in calcium oxide and sodium oxide values for the Venice and Aquileia samples reflect severe post-depositional alteration in underwater environments rather than original compositions. The pattern suggests that Roman builders did not confine themselves to a single eruption but exploited multiple Phlegraean deposits as pulvis puteolana.

A machine-learning tool added statistical rigor to the visual comparisons. Discriminant analysis, a supervised multivariate method suited to datasets with overlapping chemical features, assigned the quarry samples and mortar aggregates to specific eruptions with high probabilities. CL samples matched the Baia-Fondi di Baia eruption with probabilities from about 93 to 100 percent, LP from nearly 100 percent, and SAV, despite its geological mapping to the Neapolitan Yellow Tuff, was classified as Baia-Fondi di Baia with 95.6 to 100 percent probability, reflecting the genuine chemical overlap shared by several Phlegraean products. The literature mortar data showed primary affinity with Baia-Fondi di Baia followed by the Neapolitan Yellow Tuff, with a minor subset pointing to Monte Spina and Averno. The authors note that these probabilistic attributions rest on major-element chemistry alone and that trace-element data could sharpen future provenance assignments.

The technological test came from the Fratini test, a European standard method developed more than fifty years ago that measures how much calcium hydroxide a blended cement can consume over fifteen days of curing at 40 degrees Celsius. All three samples plotted below the calcium hydroxide solubility curve, proving genuine pozzolanic activity. The SAV sample showed the highest calcium oxide reduction at 38.6 percent, followed by CL at 30.3 percent and LP at 29.2 percent. The authors are careful to frame these results as complementary evidence: the Fratini test was designed for modern cementitious systems, and the hypothesis that Romans deliberately selected specific Phlegraean materials rests mainly on the convergence of historical quarry locations, petrographic features, reactive glass content and the geochemical match between deposits and mortar aggregates.

Why did these particular ashes work so well? The answer lies in the polymerization of the volcanic glass network. Glasses with moderate silica content, characteristic of part of the Neapolitan Yellow Tuff and Baia-Fondi di Baia products, are less polymerized and therefore dissolve more readily, accelerating the pozzolanic reaction in which silica and alumina react with calcium hydroxide at room temperature to form calcium-aluminum-silicate-hydrate gel. This C-A-S-H gel is what gives Roman hydraulic mortars their ability to harden underwater and their exceptional mechanical strength. Silica-rich glasses, by contrast, are less reactive. The shared compositional variability of the two eruptions in terms of silica content may thus be the key factor behind high-performance hydraulic mortars, and it may explain why the Romans favored these deposits without ever knowing the chemistry behind them.

The study establishes a first reference database of glass analyses for Phlegraean pozzolana, offering archaeologists a powerful tool for tracing the provenance of mortar aggregates in monuments across the former Roman Empire. It also reframes the scale of Roman resource management: the expansion of Puteoli’s harbor made the ash a strategic commodity, exported along grain-ship ballast routes to Ostia, Alexandria, Caesarea Maritima and beyond, and even carried to Constantinople, as the fifth-century historian Sidonius Apollinaris documented in his Panegyricus. Roman craftsmen, the authors conclude, possessed an advanced empirical knowledge of the raw materials of their territory, recognizing the value of many pyroclastic deposits rather than a single one. That legacy, encoded in mortars that have survived two millennia of seawater, may yet inform modern sustainable cement formulations seeking to rediscover what the Romans knew by practice alone.

Subject of Research: Provenance and selection of Roman hydraulic pozzolana from the Phlegraean Fields

Article Title: On the tracks of Pulvis Puteolana: provenance and selection of Roman hydraulic materials

Article References: Mercurio, M., Montesano, G., Cappelletti, P., Petrosino, P., Graziano, S. F., Campanile, A., Liguori, B., & Rispoli, C. (2026). On the tracks of Pulvis Puteolana: provenance and selection of Roman hydraulic materials. Archaeological and Anthropological Sciences, 18(11), Article 217. https://doi.org/10.1007/s12520-026-02582-7

Image Credits: AI Generated

DOI: 10.1007/s12520-026-02582-7

Keywords: tracks, Pulvis, Puteolana, provenance, selection, Roman, hydraulic, materials, scientific research

The research, published in the journal Frontiers in the Internet of Things, comes from the Federal University of Sergipe and the Laboratory of Technological Innovation in Health at the Federal University of Rio Grande do Norte. The team set out to solve a problem that has long frustrated auditors at Brazil’s Ministry of Health: the OPME sector, which spans everything from stents and catheters to orthopaedic prostheses and cannulas, is dominated by a bewildering variety of products from both multinational giants and small local firms. Because many public information systems still record purchases as unstructured natural language descriptions rather than standardized codes, comparing products, standardizing prices and detecting anomalies becomes a manual, error-prone chore. Worse, that lack of standardization opens space for corruption.

The stakes are enormous. The researchers cite estimates that corruption costs Brazil between 1.38 and 2.30 percent of its gross domestic product, which translates to roughly 100 to 160 billion reais based on 2019 figures. The OPME market itself gained national notoriety in January 2015, when the press exposed an alleged fraudulent scheme involving manufacturers, distributors, hospitals, doctors and lawyers, which became known as the prostheses mafia. The scheme reportedly involved selling devices at inflated prices, paying irregular commissions and outright embezzlement. The problem is not unique to Brazil: in 2017, the European Court of Auditors reported that misclassification and misdescription of goods are among the most common forms of payment evasion.

At the heart of the new tool, called OPMinEr, is a classic but powerful text-mining technique known as TF-IDF, short for Term Frequency-Inverse Document Frequency. The method works by splitting each invoice description into tokens, the individual words separated by spaces. Term frequency counts how often a word appears in a given document, while inverse document frequency measures how representative that word is across the entire corpus of documents. The final TF-IDF weight multiplies these two values, so words that appear in nearly every document receive a weight of zero, since the logarithm of one is zero. In other words, common words carry little discriminatory power, while rare, distinctive terms like specific device names stand out. This vector representation allows machine learning algorithms to treat each invoice description as a point in a high-dimensional numerical space.

Building the knowledge model required an ambitious data curation effort. The researchers assembled a data dictionary from multiple sources: product records from Brazil’s National Health Surveillance Agency (ANVISA), the federal government’s official materials register (CATMAT), descriptions entered manually by auditors, and invoices from the state of Rio Grande do Norte that were labeled by hand. A Python script automated the downloading of CATMAT files, though the team had to contend with the instability of the federal government’s website, which periodically stopped responding and forced the script to retry downloads. To semi-automatically identify OPME products within the ANVISA and CATMAT databases, the team used cosine similarity, a natural language processing technique that measures how closely two text descriptions resemble each other. Descriptions with a similarity score of 0.6 or less were initially discarded, and the remainder underwent manual review before being added to the dictionary. The team also created a standardization and conflation dictionary that acts as a synonym tool, automatically correcting truncated words like parafus into the complete form parafuso, meaning screw.

OPMinEr performs three sequential classifications. First, it predicts whether a product description corresponds to an OPME at all; if not, it is labeled as Other. Next, it assigns the product to one of 83 different classes, such as Stent, Catheter, Orthopaedic Prosthesis or Cannula. Finally, it predicts the specific Unified Health System (SUS) procedure in which the product may have been used, drawing on 319 possible procedures ranging from Detachable Balloon Placement to Tibio-Tarsal Intramedullary Stem. Each classification type required its own trained model, since different algorithms may excel at different tasks.

To evaluate the tool scientifically, the team conducted a controlled in vitro experiment using 465,726 electronic invoices from January 2020 to May 2022, obtained from AudSUS, the SUS National Audit Department, as well as from LAIS and the Federal Public Ministry. Because invoices for products that are not OPMEs vastly outnumber OPME invoices, the researchers selected a sample of 4,718 records that preserved the approximate proportion of OPME notes. Seven algorithms were compared: Multinomial, Gaussian and Bernoulli Naive Bayes, Linear Support Vector, Decision Tree, Random Forest and Gradient Boosting. The models were trained and evaluated using 10-fold cross-validation, meaning the data was divided into ten parts and the model was trained and tested ten times, with metrics averaged across iterations. The team used PostgreSQL, Python, Django, MLflow, Power BI and scikit-learn on a computer with an Intel Core i7 processor and 32 gigabytes of RAM.

The results were striking. For the Type classification, the Linear Support Vector algorithm achieved an accuracy of 99.8 percent, along with matching sensitivity, precision and F1-score of 99.8 percent, while training in just over seven seconds and classifying in 0.273 seconds. Random Forest followed closely at 99.6 percent accuracy, though it took over 221 seconds to train. Gradient Boosting, despite good accuracy, proved painfully slow, taking more than four days to train the Procedure classification data, because the algorithm builds a new decision tree in each iteration to correct the mistakes of previous trees by assigning higher weights to misclassified examples. For the Class classification, Linear Support Vector again led at 99.6 percent accuracy, and for the Procedure classification it reached 98.6 percent. Multinomial Naive Bayes was the most efficient in average training time across all three classification types, while Decision Tree was the fastest at average classification time. Bernoulli Naive Bayes collapsed on the more complex tasks, dropping to 73.5 percent accuracy for Class and a dismal 37.1 percent for Procedure, with precision of just 13.8 percent in the latter case.

The team did not rely on raw numbers alone. They applied five statistical tests: Shapiro-Wilk to check normality of the data distribution, Kruskal-Wallis and Post-Hoc Dunn for non-normal data, and ANOVA with Tukey HSD for normal distributions. With a significance level of 0.05, the tests confirmed that differences between algorithms were statistically significant. After applying the Bonferroni correction, Linear Support Vector proved significantly different from all three Naive Bayes variants in the Type classification. Interestingly, although Linear Support Vector had the highest accuracy, the statistical tests showed that Linear Support Vector and Random Forest, which approach the problem quite differently, one seeking the hyperplane that maximizes the margin between classes, the other averaging votes from many decision trees trained on different data subsets, were statistically similar in performance.

The practical payoff comes in the form of audit trails and intelligent reports for AudSUS auditors. Once invoices are classified, the system can flag anomalously high prices, unusual quantities of OPMEs purchased per inhabitant, and suspicious relationships between requesting and authorizing professionals. In one example, the system detected that out of 17,861 authorizations, 2,223, or 12.4 percent, were made by one doctor to another, with 100 percent of the first doctor’s authorizations going to the second, totaling over 4.1 million reais. Another dashboard identifies cases where the quantity of a material purchased by a health unit significantly exceeds expected demand, suggesting cold invoices or stolen stock. The researchers note that the classifier is a sine qua non condition for executing OPME audit trails, since without accurate classification, no downstream analysis is possible. Looking ahead, the team plans to explore deep learning approaches, including a hybrid metamodel incorporating BERT, a transformer-based language model that considers both preceding and following context of words, potentially offering an even more complete understanding of invoice descriptions. For now, the Linear Support Vector classifier, chosen for its superior accuracy and its ability to maximize margins between classes for strong generalization, stands as a working weapon in the fight for transparency in health resource management.

Subject of Research: A smart classifier of orthoses, prostheses and special materials (OPMEs) in invoices

Article Title: A smart classifier of orthoses, prostheses and special materials (OPMEs) in invoices

Article References: Gomes, W., Colaço Júnior, M., Alves, L. P. C. F., Fontes, R., Silva, R., Nunes, B., Silva, C., & Valentim, R. (2025). A smart classifier of orthoses, prostheses and special materials (OPMEs) in invoices. Frontiers in the Internet of Things, 4, Article 1436757. https://doi.org/10.3389/friot.2025.1436757

Image Credits: AI Generated

DOI: 10.3389/friot.2025.1436757

Keywords: artificial intelligence, machine learning, healthcare fraud, text classification, public auditing, Brazil, smart, classifier, orthoses, prostheses, special, materials

Engineered Living Materials, or ELMs, integrate living cells within engineered scaffolds to create adaptive and responsive functions. Living artefacts extend this approach by incorporating living organisms as active participants in designed objects, where biological activity contributes to ongoing responsiveness, interaction, and new forms of human–living system relationships. Both approaches have expanded the role of biology in design, positioning living systems as functional and tuneable components. However, current applications remain largely confined to discrete objects or material components, meaning microbial life in design is often spatially bounded and considered at short temporal scales. This limits the ability to engage with microbial systems as distributed ecological networks across built environments.

The archibiome concept addresses this gap by defining the subset of the built-environment microbiome that is intentionally shaped through architectural and material interventions. It includes both engineered microorganisms introduced through ELMs and native microbial communities whose recruitment, selection, and interactions are modulated through design strategies. Conceptually, the archibiome treats the built environment as a multiscale, feedback-controlled system integrating microbial community dynamics, engineered materials, and environmental conditions. Microbial processes are coupled to architectural parameters such as material composition, spatial configuration, moisture, light, and temperature through feedback loops in which system outputs influence future system states. This enables the prediction and regulation of system-level functions such as carbon sequestration, pollutant degradation, oxygen production, and self-regeneration.

Existing terms like building microbiomes, indoor microbiomes, and urban microbiome are primarily descriptive, characterizing microbial assemblages as emergent outcomes of environmental and design conditions without distinguishing whether or how these communities are intentionally shaped. The archibiome differs by framing microbial communities as integral, designable ecosystems distributed within architectural and infrastructural systems. Rather than focusing on isolated artefacts, the framework addresses how microbial processes are distributed and coordinated across spatial, temporal, and infrastructural scales, including their interactions with environmental conditions and human occupants. ELMs act as enabling technologies through which microbial functions can be engineered, monitored, and controlled, while living artefacts represent localized implementations within a broader ecological system.

Depending on their design, ELMs can perform biocatalytic functions such as bioremediation and carbon sequestration, bioreceptive functions such as protection and self-healing, and responsive functions such as sensing and signalling. The intrinsic capacity of ELMs for self-regeneration and self-healing can substantially reduce maintenance requirements and material replacement over time, aligning with circular bioeconomy principles by lowering resource consumption and enhancing the environmental sustainability of building systems. The archibiome is not only defined by intentional design but by the explicit integration of microbial dynamics with architectural control parameters, focusing on how microbial communities are regulated through spatially distributed gradients and feedback mechanisms including nutrient fluctuations, moisture regimes, material properties, and environmental exposure.

The importance of this framework is profound, particularly as modern humans spend up to 90 percent of their lives indoors. This prolonged exposure means indoor microbial communities, being an integral part of the exposome, play a critical role in shaping human health and wellbeing. Indoor air quality, exposed surfaces, and building materials shape the microbial landscape we interact with daily. While increasing evidence suggests associations between indoor microbial communities and human health, these relationships remain largely correlational, and further work is required to establish causal mechanisms and evidence-based design strategies. Designing indoor spaces with microbial ecosystems in mind therefore represents a promising but still emerging approach with direct implications for sustainability, as microbial communities contribute to carbon and nutrient cycling, pollutant degradation, and environmental buffering.

Adopting an archibiome perspective also raises challenges beyond design and material integration. Engineering microbial ecosystems at the scale of buildings requires careful attention to long-term dynamics, system stability, and unintended ecological consequences. It intersects with regulatory frameworks that are still evolving, particularly for products that intentionally introduce living microorganisms into built environments. Each ELM product is inherently unique, containing different organisms and having different functions and intended uses, meaning one-size-fits-all regulatory pathways are insufficient. Regulatory uncertainty can slow the translation of research into practice, as extensive testing is required to demonstrate safety, efficacy, and ecological compatibility. In both the European Union and the United States, agencies enforce strict biosafety regulations that consider the potential spread of microorganisms beyond the targeted environment. If genetically modified microorganisms are involved, additional requirements address their origin, genetic modifications, and potential for horizontal gene transfer.

Public perception is another critical factor. Concerns include uncontrolled microbial growth, allergenic responses, and survival of pathogenic organisms in sensitive environments such as hospitals or schools. These issues highlight the need for transparent communication and robust safety classification systems such as Qualified Presumption of Safety, Risk Group classifications, and FDA GRAS frameworks. Ensuring long-term stability and safety of ELMs requires both physical and biological containment strategies. Hydrogels, thermogels, and synthetic or natural polymers can physically constrain microbial growth, while genetic and metabolic engineering of microorganisms limits their survival, proliferation, or gene exchange outside intended conditions through approaches such as auxotrophy, kill-switches, or dependency on specific substrates. These approaches demonstrate the feasibility of creating living materials that are controllable, safe, and predictable.

From a systems biology perspective, the archibiome can be formalized as a coupled multiscale dynamical system linking intracellular regulatory networks, interspecies interactions, and environmentally mediated boundary conditions. At the microscale, stochastic or constraint-based metabolic models can describe microbial responses to environmental stimuli including nutrient availability, stress, and signalling dynamics. At the mesoscale, large hierarchical and consumer–resource models can capture competitive and cooperative dynamics governing community assembly and functional stability. At the macroscale, Building Information Modelling or computational fluid dynamics can represent processes and environmental heterogeneity in the built environment. These modelling layers can be integrated into a unified hybrid framework in which microbial dynamics are coupled to time-varying environmental fields defined by architectural parameters such as airflow, humidity gradients, surface chemistry, and material porosity, enabling the formulation of the built environment as a feedback-controlled ecological system.

Emerging research projects illustrate how the archibiome concept can be operationalized in practice. The ARCHI-SKIN project develops living coating systems based on the biofilm-forming fungus Aureobasidium pullulans, designed to protect building materials through self-regenerating and metabolically active layers. In this context, microbial performance is not only determined by species selection but by the interaction between substrate properties, nutrient availability, and environmental conditions. Complementary to this approach, the REMEDY project explores the integration of designed microbial consortia as living inks for architectural surfaces, combining functions such as carbon sequestration, pollutant remediation, and microbial balance with spatial patterning and digital fabrication strategies. For living active inks developed for architectural surfaces targeting carbon sequestration up to 15 kg CO2 per 10 square meters per year, oxygen production via photosynthesis up to 10 kg O2 per 10 square meters per year, self-regeneration with healing distance up to 2 millimeters, and bioremediation up to 140 kg VOCs per cubic meter of air per year, it can be hypothesized that spatial variation in environmental exposure such as light intensity, moisture availability, temperature, and airflow regimes will differentially modulate microbial metabolic activity and community composition across building surfaces. This hypothesis can be operationalized by predictive models of microbial growth and metabolite exchange with computational fluid dynamics simulations of airflow, light distribution, and humidity gradients, enabling prediction of spatially resolved performance metrics. Empirical validation can then be achieved through meta-omics data combined with in situ measurements of CO2 uptake, O2 production, and VOC degradation under both controlled and natural weathering conditions. Such an approach directly links design variables like façade orientation, material porosity, and environmental buffering capacity with quantifiable ecological and functional outcomes, supporting iterative refinement of both models and archibiome-informed design strategies. Ultimately, the archibiome does not diverge from the ELM field but extends its conceptual and operational boundaries, highlighting how advances in ELMs, synthetic biology, and systems biology can converge to support the development of adaptive, multifunctional built environments and marking a shift from descriptive to predictive and engineering-driven approaches to living systems in architecture.

Subject of Research: Microbial Ecology and Architecture

Article Title: The archibiome: extending engineered living materials to multiscale built environments

Article References: Sandak, A., Pajerski, W., Gubenšek, A., Butina Ogorelec, K., & Černoša, A. (2026). The archibiome: extending engineered living materials to multiscale built environments. Frontiers in Systems Biology, 6, Article 1943876. https://doi.org/10.3389/fsysb.2026.1943876

Image Credits: AI Generated

DOI: 10.3389/fsysb.2026.1943876

Keywords: archibiome, engineered living materials, built environment, microbiome, probiotic design, regenerative architecture, synthetic biology, systems biology, extending, engineered, living, materials

In a Perspective published in Frontiers in Batteries and Electrochemistry, Minseok Kim, Jungmin Lee, and colleagues under the supervision of Dongsoo Lee and Junghyun Choi lay out a co-design strategy that connects silicon materials, electrode architecture, interfacial chemistry, and processing technology into a single integrated framework. Their central claim is provocative: the challenges that plague silicon anodes cannot be solved by optimizing the active material alone. Instead, practical, high-energy-density silicon anodes will require holistic electrode engineering in which every component, from binders to electrolyte additives, is treated as an active design parameter.

The scale of the silicon problem is easy to underestimate. When silicon absorbs lithium ions during charging, it swells by up to 300 percent in volume. That mechanical breathing cycle pulverizes particles, breaks electrical contacts, and repeatedly ruptures and reforms the solid electrolyte interphase, the thin protective layer that forms on the anode surface. Each rupture consumes fresh lithium and electrolyte, driving rapid capacity decay and eventual cell failure. Graphite, by contrast, swells only modestly and stores just 372 milliampere-hours per gram, which is why it has remained the commercial standard despite its fundamental capacity ceiling.

Over the past decade, researchers have made remarkable progress at the material level through nanostructuring, alloying, and composite design, including silicon oxide and silicon-carbon composites. Cui and coworkers demonstrated that well-ordered graphene coatings on silicon particles, engineered through thermal oxidation followed by chemical vapor deposition, preserve structural integrity far better than disordered carbon coatings. Cho’s group has pushed scalable implementations further, engineering sub-nanometer silicon anodes through a crystal growth inhibition mechanism and demonstrating structural stability in practical prototype battery packs. The Gachon team’s own contributions include graphene nanoribbon-based conductive networks that enhance microstructural homogeneity and mechanical robustness in silicon-carbon composite anodes, as well as 2D structured graphite frameworks that accommodate the anisotropic swelling of silicon domains while maintaining inter-particle connectivity.

But here is where the lab-to-factory gap becomes apparent. Most laboratory demonstrations of nanostructured silicon rely on low areal loadings below 1 milliampere-hour per square centimeter and flooded electrolyte conditions that do not reflect real cell constraints. Many nanostructuring approaches, such as templated synthesis of porous silicon or chemical vapor deposition of conformal carbon coatings, face significant barriers in scalability and cost-effectiveness. The Gachon researchers argue that this discrepancy between laboratory performance and industrial feasibility demands a co-design philosophy that bridges material innovations with scalable electrode engineering from the outset, rather than treating manufacturing as an afterthought.

At the electrode level, the team highlights how conductive agents and binders have evolved from passive components into active structural elements. Polyanion-assisted ionic-electronic conductive agents developed for high-density silicon-based anodes can preserve electrical percolation pathways even under severe electrode breathing while facilitating electrolyte penetration throughout the electrode. Binders, once mere adhesives, must now accommodate significant mechanical stress and preserve electrode integrity through repetitive volume fluctuations. Systems such as pulley and self-healing binders have been introduced to address electrode cracking, and the Gachon group proposes multifunctional network binders featuring mechanically robust crosslinked frameworks that substantially enhance structural stability. This design concept becomes even more critical in all-solid-state batteries, where interfacially reinforced crosslinked binders can alleviate severe contact-loss issues at solid-solid interfaces.

Processing technology represents another frontier. Because silicon anodes are typically commercialized in blended configurations with graphite, thick-film electrodes are essential for maximizing practical capacity and energy density. Dry electrode processing has emerged as a promising manufacturing route because it mitigates solvent-induced binder migration, a major bottleneck of conventional wet-based processing for high-loading anodes. However, dry-processed anodes present unique interfacial challenges, particularly those associated with binder decomposition. Tailored electrolyte additive designs are vital for suppressing initial irreversibility in dry-processed electrode matrices, significantly enhancing electrochemical stability in full-cell configurations. Chemical modifiers such as carboxy silanes can direct robust solid electrolyte interphase formation and ensure stable operation even under high areal capacity conditions of 3.5 milliampere-hours per square centimeter.

Overcoming the inherently low initial Coulombic efficiency of silicon anodes, which largely originates from extensive solid electrolyte interphase formation, requires electrode-level prelithiation engineering. The Gachon team’s earlier work showed that incorporating silicon-stabilized lithium metal powder composites enables controlled in situ prelithiation. More recently, they extended this concept to scalable fully dry manufacturing with a lithium-metal-underlayer-based Li/Cu prelithiation strategy. In this simple one-step dry process, the lithium underlayer compensates for initial lithium loss in thick-film anodes while promoting the bottom-up formation of a uniform fluorine-rich solid electrolyte interphase.

The co-design philosophy extends to interfacial chemistry as well. Mechanochemically activated additives strengthen interactions within silicon-carbon composite electrodes, enabling uniform dispersion, a robust matrix that tolerates severe volumetric stress, and improved solid electrolyte interphase stability during cycling. Building on this concept, interface-stabilizing anion-anchoring additives were developed to address non-uniform lithium-ion flux and localized overpotentials arising from tortuous transport pathways. Through sulfonate-driven electrostatic stabilization and interfacial anion anchoring, these additives create a lithium-ion-enriched interfacial environment that homogenizes flux and directs solid electrolyte interphase evolution toward a thin, robust, lithium-fluoride-rich inorganic interphase. Surface-engineering strategies that induce lithium-fluoride-rich interphases, including a synergistic hybrid interlayer termed Anode SHIELD, enhance interfacial stability by mechanically isolating the active surface while increasing the lithium-ion transference number and promoting facile transport. These protective interlayers can also mitigate dendrite growth and short-circuit risks under abnormal cell behavior, and the strategy extends beyond conventional lithium-ion batteries to pure silicon anodes in high-power lithium-ion capacitors.

Looking ahead, the Gachon researchers outline a quantitative roadmap for the next stage of silicon-anode development. Future research should prioritize high-loading, thick-film electrodes above 5.0 milliampere-hours per square centimeter specifically optimized for extreme fast charging, targeting 80 percent state-of-charge in under 15 minutes while addressing localized polarization and lithium-plating risks. Interfacial engineering must extend to solid-state battery configurations, where the primary challenge shifts to maintaining chemo-mechanical contact through breathable interfaces that accommodate silicon expansion without delaminating from solid electrolytes. Scalable processing routes, particularly dry manufacturing and integrated prelithiation strategies, should be refined to ensure uniform prelithiation and binder distribution at industrial scale, targeting production throughput comparable to current graphite-based lines. To satisfy the demanding performance requirements of electric vehicles, robotics, and urban air mobility, the field must establish a quantitative roadmap targeting at least 1,000 end-of-life cycles and energy densities exceeding 400 watt-hours per kilogram and 800 watt-hours per liter at the cell level. The future of silicon anodes, the team concludes, will depend not simply on discovering better silicon materials, but on establishing a holistic design philosophy that unifies material innovation, electrode engineering, and scalable manufacturing into a tightly integrated electrode system.

Subject of Research: Bridging silicon materials and electrode engineering for high energy density lithium ion battery anodes

Article Title: Bridging silicon materials and electrode engineering for high energy density lithium ion battery anodes

Article References: Kim, M., Lee, J., Lee, C., Kim, J., Jo, W., Lee, D., & Choi, J. (2026). Bridging silicon materials and electrode engineering for high energy density lithium ion battery anodes. Frontiers in Batteries and Electrochemistry, 5, Article 1848415. https://doi.org/10.3389/fbael.2026.1848415

Image Credits: AI Generated

DOI: 10.3389/fbael.2026.1848415

Keywords: Bridging, silicon, materials, electrode, engineering, high, energy, density, lithium, battery, anodes, scientific research

To understand why a single percentage can matter so much, it helps to grasp what semi-flexible pavement actually is. Engineers begin with an open-graded porous asphalt mixture, in this case a PAC-13 blend with a nominal maximum aggregate size of 13 millimeters and a void content typically ranging from 20 to 30 percent. Into this sponge-like skeleton they infuse a high-fluidity cement slurry, creating a hybrid that combines the smoothness, skid resistance, and ease of repair of asphalt pavement with the high strength and modulus of cement concrete pavement. The concept emerged as a direct response to a stubborn problem: asphalt is a viscoelastic-plastic material, exquisitely sensitive to temperature, and in hot summers it develops ruts earlier, more frequently, and with greater deformation depth than in cooler seasons. Semi-flexible pavement tames this weakness, but its performance hinges on how much grouting space the matrix provides, which is determined almost entirely by the void content of the underlying asphalt mixture.

The researchers left nothing to chance in controlling their variables. The grouting material was a self-developed blend of ordinary Portland cement, aluminate cement, fly ash, silica fume, fine quartz sand, latex powder, and water-reducing agent, mixed with water at a ratio of 0.3 and blended at 4,000 revolutions per minute for two minutes in a high-speed shearing machine. The slurry exhibited an initial flow cone fluidity of 12.9 seconds, a pre-hardening setting time of 188 minutes, a density of 1.919 grams per cubic centimeter, and impressive early strength, reaching 28.6 megapascals in compression within one day and 33.7 megapascals at 28 days. The matrix mixtures, meanwhile, were built from gabion coarse aggregate with an apparent relative density of 2.943 and a needle-like particle content of just 1.8 percent, limestone fine aggregate, limestone mineral powder, and styrene-butadiene-styrene modified asphalt with a softening point of 91 degrees Celsius. Three aggregate gradations, labeled G1, G2, and G3, were designed with optimum asphalt-aggregate ratios of 3.2, 3.4, and 3.5 percent, and specimens were Marshall-compacted with 50 blows per side at temperatures between 155 and 160 degrees Celsius.

The first performance indicator the team examined was the perfusion rate, defined as the ratio of the actual volume of cement slurry retained within the matrix after grouting to the connected void volume available before grouting. The measurements revealed an almost perfect linear relationship between the total void ratio and the connected void ratio, with a correlation coefficient of 0.998, confirming that the two indices move in lockstep and that either can serve as the governing design variable. As the void content increased, the perfusion rate climbed steadily, and, just as tellingly, the standard deviation of the filling rate shrank. In practical terms, higher void content does not merely let more slurry in; it lets the slurry in more uniformly. The explanation lies in the pore architecture of the matrix: as void content decreases, the available connected space and effective channels for slurry penetration narrow, raising resistance to infiltration and producing a heterogeneous, discontinuous distribution of grout that leaves weak spots scattered through the composite.

Then came the mechanical payoff, and it was spectacular. Marshall stability tests at 60 degrees Celsius and splitting tests at 15 degrees Celsius showed that grouting transformed the composites at every void level, but the magnitude of the transformation scaled dramatically with the matrix voids. At 20.6 percent void content, grouting boosted stability by a factor of 1.2 and splitting strength by 0.3; at 24.9 percent, the gains rose to 2.5 and 1.0 respectively; and at 29.2 percent, stability soared by a factor of 4.8 while splitting strength increased 1.4-fold. After grouting, the Marshall stability of the semi-flexible material ranged from 17 to 30 kilonewtons across the tested void contents. The pattern reverses when the ungrouted matrices are considered alone: the higher the void content, the weaker the bare PAC-13 mixture, yet the stronger the final composite. This inversion carries a profound design implication, because it shows that the mechanical properties of semi-flexible pavement depend mainly on the strength of the cement slurry and the filling rate, not on the strength of the underlying asphalt skeleton. Excessively high mechanical performance in the matrix is unnecessary; only sufficient stability to survive field compaction is required.

Cracking resistance, however, told a far more nuanced story, one that varied with temperature in ways that previous studies had never fully reconciled. Using trabecular specimens of 250 by 30 by 35 millimeters extracted from rut plates, the team ran three-point bending tests at both minus 10 and 15 degrees Celsius. At minus 10 degrees Celsius, the flexural tensile strength of the composites was roughly twice that measured at 15 degrees Celsius, while the maximum flexural tensile strain was far smaller, because the asphalt phase behaves rigidly and tends toward brittle failure. When the void ratio rose from 20.6 to 24.9 percent at the cold temperature, the flexural tensile strain reached its maximum of 2,020 microstrain, an 8 percent enhancement signaling better crack resistance. But pushing the void content to 29.2 percent caused the strain to plummet to 1,494 microstrain, a 26 percent decline. The physics is elegant: at low void content, incomplete perfusion leaves interconnected voids that concentrate stress and accelerate cracking; at moderate void content, more uniform grout distribution evens out internal forces; but beyond 24.9 percent, the cement slurry content becomes excessive, the asphalt mastic content too small, and the overall stiffness so high that the coordinated deformation ability of the two phases is weakened.

At 15 degrees Celsius the hierarchy flipped entirely. There, the asphalt mixture retains viscoelastic plasticity and good deformation ability, so lower void content, meaning higher asphalt mastic content and lower overall rigidity, produced superior crack resistance, with flexural tensile strain decreasing gradually as void content increased. The team noted that the higher the temperature, the more pronounced the effect of void ratio on the flexural tensile strain, and conversely, the lower the void ratio, the more sensitive the maximum flexural strain became to test temperature. This temperature-dependent reversal explains why earlier studies had reached seemingly contradictory conclusions, with some reporting that larger matrix voids monotonically improved cracking resistance while others found an optimum near 24 percent. Both camps were right, but each was describing a different thermal regime, and neither had systematically quantified the trade-off within a single complete performance framework.

High-temperature deformation resistance and water stability, the twin pillars of pavement durability, both favored higher void content. In 60-degree rutting tests, the dynamic stability of the composites climbed as matrix voids increased, with the rate of improvement fastest below 24.9 percent: raising the void ratio from 20.6 to 24.9 percent added 10,837 cycles per millimeter, a 63.6 percent enhancement, while the further increase to 29.2 percent contributed only 2,803 cycles per millimeter, a mere 10 percent gain. The freeze-thaw splitting tensile strength ratio, meanwhile, increased linearly with void content, gaining 2.1 percentage points from 20.6 to 24.9 percent and another 2.5 points up to 29.2 percent. The mechanism is straightforward: higher perfusion rates mean fewer communicating voids remain in the finished composite, so less water enters the interior during freezing and thawing cycles, reducing internal damage. The rigid cementitious skeleton, once fully formed, provides strong resistance to permanent deformation, which is why all grouted specimens exhibited relatively high dynamic stability regardless of matrix void content.

The convergence of all these threads points to a single recommendation that could reshape design practice. Current specifications merely advise a void content range of 20 to 30 percent for the matrix asphalt mixture without offering a clear optimum, leaving engineers without a scientific basis for selection. The new study fills that gap with multi-performance synergy analysis: below 24.9 percent, increasing voids significantly enhances resistance to high-temperature deformation; at 24.9 percent, the material balances mechanical properties, high-temperature performance, water stability, and cracking resistance most evenly; and beyond that threshold, further void increases yield limited high-temperature gains and actively degrade cold-temperature crack resistance. The authors suggest this shift moves semi-flexible pavement design from single-index control toward comprehensive performance balance, providing an experimental foundation for mixture design, matrix void control, and specification improvement.

For a material deployed at bus stations, intersections, and steep urban grades across China, the implications ripple outward quickly. Semi-flexible pavement still faces hurdles, including high initial construction costs from expensive grouting materials, demanding field procedures requiring strict control of grouting temperature, timing windows, curing conditions, and specialized equipment, and long-term behavior under repeated traffic and climatic loading that remains incompletely characterized. By pinpointing the matrix void content as the decisive, controllable variable, the study offers engineers a lever they can pull with confidence, one that determines the grouting space, the composite structure, and ultimately whether the pavement endures or cracks. The secret number of the road, it turns out, was hiding in plain sight all along, and now it has a recommended value: 24.9 percent.

Subject of Research: Study on the influence of matrix asphalt mixture air voids on the performance of semi-flexible pavement materials

Article Title: Study on the influence of matrix asphalt mixture air voids on the performance of semi-flexible pavement materials

Article References: Chen, J., Yang, Z., Huang, H., Lei, J., & Xuan, W. (2026). Study on the influence of matrix asphalt mixture air voids on the performance of semi-flexible pavement materials. Frontiers in Materials, 13, Article 1930537. https://doi.org/10.3389/fmats.2026.1930537

Image Credits: AI Generated

DOI: 10.3389/fmats.2026.1930537

Keywords: influence, matrix, asphalt, mixture, voids, performance, semi-flexible, pavement, materials, scientific research