The review systematically surveys five major families of in-situ techniques, each occupying a different rung on the ladder of spatial resolution. At the top of that ladder, in terms of both scale and penetrating power, sit in-situ X-ray diffraction and synchrotron radiation methods, together with X-ray computed tomography. Diffraction probes the lattice itself, tracking changes in crystal structure, lattice parameters, and phase fractions with sub-nanometer precision. Synchrotron sources, which generate X-rays orders of magnitude brighter than laboratory tubes, allow these measurements to be collected in milliseconds or faster, so researchers can follow phase transformation kinetics as a material deforms. Computed tomography extends the view into three dimensions, reconstructing the internal architecture of a bulk component non-destructively and enabling so-called 4D studies in which the third spatial dimension is joined by time as the fourth.

The authors highlight striking examples of what these synchrotron methods can now reveal. In load-partitioning studies of multiphase alloys, in-situ diffraction can measure how each crystallographic phase in a composite or duplex material individually carries the applied stress, showing how the load is transferred between phases as deformation proceeds. In damage evolution studies of carbon fiber-reinforced silicon carbide composites, synchrotron in-situ tomography combined with deep learning has tracked coupled damage across a full oxygen concentration gradient at elevated temperature, even uncovering an oxygen-diffusion shielding mechanism that governs the thermo-mechanical-oxidative behavior of these ceramics. Similar approaches have mapped microcrack evolution in fiber-reinforced recycled concrete, characterized chloride-contaminated mortar under compression, and followed corrosion of aluminum alloys under combined thermal and chloride conditions.

Between the atomic and the component scales sits digital image correlation, or DIC, a technique that the review treats as the workhorse of full-field surface strain measurement. DIC works by comparing successive digital images of a specimen surface, typically decorated with a fine speckle pattern, and computing the displacement and strain fields that best map one image onto the next. The result is a complete two-dimensional or three-dimensional map of deformation, rather than a handful of point measurements. When performed through the lens of a scanning electron microscope, SEM-DIC can resolve strain fields down to the microstructural level, revealing how individual grains deform, where strain localizes, and where damage nucleates. The cited literature shows the breadth of this approach: measuring deformation kinematics during orthogonal cutting of titanium alloys, quantifying heterogeneous plastic deformation and so-called HDI strengthening in dual-phase steels, tracking strain localisation in particle-reinforced aluminum composites at high temperature, and even characterizing the mechanics of soft biological tissues such as the tricuspid valve.

The review then turns to electron microscopy-based methods, beginning with in-situ scanning electron microscopy itself. In an SEM, a tensile, fatigue, heating, or corrosion stage can be mounted inside the vacuum chamber, and the beam scans across the sample surface in real time. This allows researchers to watch crack initiation, propagation, and closure with sub-micrometer resolution while simultaneously correlating what they see with the applied load. The cited studies span fatigue short-crack growth in microscale single-crystal copper, slip-controlled fatigue crack growth in nickel-based bicrystal superalloys, hydrogen-charging effects on low-cycle fatigue of titanium alloys, and phase transformation and twinning mechanisms in interstitial high-entropy alloys. A growing trend noted in the review is automation and machine learning: spatiotemporal SEM image sequences are now being used to predict remaining fatigue life through domain-adaptive deep learning models, converting qualitative observation into quantitative forecasting.

Electron backscatter diffraction, EBSD, adds crystallographic information to the microscopic picture. Mounted on an SEM, an EBSD detector captures diffraction patterns from each scanned point on the surface and determines the local crystal orientation. In-situ EBSD experiments—deforming a sample inside the microscope and periodically mapping the orientation field—reveal how grains rotate, how deformation twins nucleate and grow, and how strain partitions among grains with different orientations. The review cites work on twinning in magnesium alloys, deformation mechanisms in high-entropy alloys, abnormal grain growth in nickel-based superalloys and high-purity cobalt, and the reverse transformation of austenite from lath martensite in steels. Quasi-in-situ EBSD, in which the sample is unloaded and remounted between mapping steps, extends these capabilities to fatigue and weld studies where continuous observation is impractical, and increasingly EBSD data are being fed directly into crystal plasticity finite element models to validate simulated grain reorientation trajectories.

At the finest scale lies in-situ transmission electron microscopy. TEM pushes spatial resolution to the atomic level, and modern instruments can be equipped with heating, cooling, tensile, nanoindentation, electrochemical, and irradiation stages. This means researchers can watch individual dislocations glide, stacking faults form, precipitates coarsen, grain boundaries migrate, and radiation damage accumulate—all in real time. The cited literature is remarkable in its scope: dislocation dynamics in high-entropy alloys analyzed with deep learning pipelines, irradiation-induced void swelling in nickel analyzed with computer vision, heavy-ion irradiation of zirconium alloys revealing interactions between defects and hydrogen atoms, lithium and sodium storage mechanisms in battery electrode materials observed during charging, and the growth of reaction layers in thin-film diffusion couples. Liquid-phase and cryo-TEM extend this capability to solutions and frozen states, enabling direct visualization of electroplating, ice nucleation, and phase separation.

What emerges from the review is not a picture of competing techniques but of complementary ones, each with defined applicable boundaries. X-ray methods penetrate bulk materials but average over larger volumes; electron microscopy resolves fine detail but only thin specimens or surfaces. DIC measures full strain fields but requires line-of-sight access to a prepared surface. The most powerful modern studies combine several techniques simultaneously—diffraction with DIC, SEM with EBSD, CT with digital volume correlation—to span the scales from lattice to component. The review emphasizes that this multiscale, real-time observational capability is what allows researchers to attack the central scientific problems of materials mechanics: load partitioning in multiphase alloys, three-dimensional damage evolution, phase transformation kinetics, and fatigue fracture, all under coupled multi-field service conditions that no static measurement can reproduce.

Yet the review is candid about four core challenges. The first is the inherent trade-off between spatial and temporal resolution: fast, high-resolution measurements demand brilliant sources and sensitive detectors, and improving one dimension often sacrifices the other. The second is the difficulty of reproducing extreme service environments—combining high temperature, reactive atmospheres, mechanical loading, and radiation in a single experimental window remains an engineering feat, and the sample environments themselves can introduce artifacts, as studies of electrochemical dead zones in in-situ XRD cells demonstrate. The third is the data deluge: in-situ experiments generate massive multimodal datasets—terabytes of images, diffraction patterns, and tomographic reconstructions—whose analysis increasingly depends on machine learning, from deep-learning segmentation of CT damage to automated dislocation tracking in TEM videos. The fourth is the non-uniqueness dilemma in model inversion: extracting microscopic parameters such as cohesive-zone laws from diffraction strain fields involves solving ill-posed inverse problems where many parameter sets can fit the same data.

The significance of this synthesis extends well beyond instrumentation. By establishing a critical theoretical foundation for dynamic, cross-scale observation, the review aims to support the construction of the processing–structure–property relationships that underpin modern materials design, from aerospace superalloys and fusion reactor materials to batteries, cement, and additive-manufactured components. When engineers can see, in real time and across six orders of magnitude in length scale, how a microstructure actually evolves under the coupled fields of real service, they can design materials from mechanism rather than from correlation. In that sense, the era of watching materials think—deform, transform, and fail in real time—is not merely a technical achievement but a conceptual shift in what it means to understand a material.

Subject of Research: Cross-scale in-situ characterization techniques for tracking dynamic microstructural evolution in materials under coupled multi-field conditions

Article Title: Review:cross-scale in-situ characterization techniques for dynamic evolution of microstructures in materials under multi-field coupling

Article References: Liu, F., Zhang, M., Zhang, F., Li, J., Xie, H., Wang, Q., & Huan, Y. (2026). Review:cross-scale in-situ characterization techniques for dynamic evolution of microstructures in materials under multi-field coupling. Journal of Materials Science, 61(41), 31707-31770. https://doi.org/10.1007/s10853-026-13674-z

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13674-z

Keywords: in-situ characterization, synchrotron X-ray diffraction, X-ray computed tomography, digital image correlation, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, microstructure evolution, multi-field coupling, phase transformation, fatigue and damage, materials characterization

The research, led by Guowei Yang, Yinlu Deng, and colleagues at Zhejiang University, focused on two cytorhabdoviruses: rice stripe mosaic virus (RSMV), a pathogen of rice in the genus Betacytorhabdovirus, and tomato yellow mottle-associated virus (TYMaV), an Alphacytorhabdovirus studied in the model plant Nicotiana benthamiana. Plant rhabdoviruses are a substantial group, comprising at least 269 species across 12 genera in the family Rhabdoviridae. Most produce bullet-shaped or bacilliform virions wrapped in a lipid envelope and are transmitted by sap-feeding hemipteran insects such as leafhoppers, planthoppers, aphids, and whiteflies in a persistent-propagative manner. Their genomes encode five conserved structural proteins—nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G), and the large polymerase (L)—plus a movement protein belonging to the 30K superfamily.

During replication, the viral RNA is encapsidated by N in association with P and L to form nucleocapsids, which previous work has established as the minimal infectious units for cell-to-cell movement. The movement protein interacts with N and P to redirect these nucleocapsids through plasmodesmata. Separately, the M protein condenses nucleocapsids into tightly coiled complexes and drives budding through G-enriched host endomembranes, producing enveloped particles that accumulate in the lumen of the nuclear envelope in nucleorhabdoviruses or the endoplasmic reticulum in cytorhabdoviruses. Whether these endomembrane-trapped virions are simply terminal assembly products or active participants in vascular trafficking has been a long-standing open question, particularly because plant rhabdovirus particles have never been observed within or around desmotubules, the ER-derived tubes that thread through plasmodesmata.

To address this, the team first mapped the spatial distribution of RSMV in infected rice using immunofluorescence staining of cryosections with an N protein-specific monoclonal antibody. In both leaf and stem sections, viral antigens were predominantly localized to vascular tissues, including xylem and phloem-associated regions, surrounding parenchyma and bundle sheath cells, and, in leaves, hypodermal sclerenchyma. Strong fluorescence appeared in infected samples while healthy controls showed none, confirming assay specificity. However, immunofluorescence could not resolve the structural form of the virus at these sites, so the researchers turned to transmission electron microscopy (TEM) on ultrathin resin-embedded sections.

The TEM results were striking. Mature enveloped RSMV virions, roughly 50 to 60 nanometers in diameter, accumulated abundantly in xylem parenchyma cells surrounding mature vessel elements, often arranged in orderly arrays within enclosing vesicle-like membranes that occupied a substantial portion of the cytoplasmic space. More remarkably, bacilliform particles with or without an enclosing membrane were detected within the lumens of mature xylem vessels themselves—hollow, dead conduits that have undergone programmed cell death and lost all cytoplasmic contents. Such particles appeared in 5 of 46 vessel-containing fields examined. Because fixing and detecting material inside these large lumens is technically difficult, the observation is all the more significant. The team also found membrane-enclosed mature virions in sclerenchyma cells that retain little cytoplasm, suggesting that RSMV particles can persist through advanced stages of cellular autolysis.

To corroborate these ultrastructural findings, the researchers collected xylem sap from the stems and roots of infected rice plants using vacuum infiltration and centrifugation, taking care to exclude cytoplasmic contamination with a glucose-6-phosphate dehydrogenase activity assay. Immunoblotting with antisera raised against purified RSMV virions detected four major protein bands in stem sap whose migration patterns matched the N, P, M, and G structural proteins of purified virions; root sap showed distinct G and M signals. Negative-stain TEM of concentrated sap then revealed bacilliform particles approximately 65 nanometers in diameter with morphology characteristic of plant rhabdovirus virions, the slightly larger apparent size reflecting differences in sample preparation and staining. Together, these data demonstrate that intact enveloped virions, not just soluble proteins or nucleocapsids, are present in the xylem translocation stream.

The phloem told a parallel story. In infected rice stems, the team identified sieve element–companion cell complexes containing virus particles, using sieve element plastids and pore-plasmodesmal units as diagnostic landmarks. Bacilliform particles consistent with mature enveloped RSMV virions were observed within both companion cells and sieve elements, with most virions in sieve elements occurring in clusters enclosed by vesicle-like membranes. Virions were found in 8 of 62 sieve element-containing fields. The same pattern held in the second pathosystem: in TYMaV-infected N. benthamiana, enveloped virions were detected in immature vessel elements that still retained residual cytoplasm, in fully differentiated vessel elements with patterned wall thickening and no protoplasmic contents, and in phloem sieve elements with or without an evident surrounding vesicle. Across the observations, enveloped virions appeared in at least 3 immature vessels, 7 mature vessels, and 6 sieve element-containing fields.

The decisive experiment came from reverse genetics. The researchers constructed TYMaV-ΔM:RFP, an infectious clone in which the matrix protein gene was replaced with a red fluorescent protein reporter while a green fluorescent protein reporter was retained. In diluted agroinoculation assays designed to test cell-to-cell movement, the mutant behaved essentially like the wild type: isolated fluorescent single cells appeared at 6 to 7 days post inoculation and foci expanded to roughly 12 cells on average by 10 days for both viruses. Immunoblotting showed GFP accumulating to slightly higher levels in mutant-infected tissues, likely because the M protein normally suppresses viral RNA synthesis. Yet negative-stain and immunogold TEM revealed that the mutant failed to assemble any detectable mature virions; gold labeling was distributed over viral material lacking recognizable virion morphology rather than decorating intact particles.

When the researchers inoculated plants under conditions permitting systemic infection, the phenotypes diverged dramatically. Wild-type TYMaV spread extensively, producing systemic GFP fluorescence from about 10 days post inoculation followed by typical mottling and leaf distortion in upper leaves, and systemically infecting 59 of 60 plants by 21 days. The M deletion mutant, by contrast, produced no systemic fluorescence or symptoms in any of 60 inoculated plants throughout the observation period. Deletion of the matrix gene thus abolished long-distance movement completely while leaving local cell-to-cell propagation intact—a phenotype that directly links virion morphogenesis to vascular dissemination.

Integrating these results, the authors propose a model in which enveloped virions serve as a major mobile entity for rhabdovirus systemic trafficking through both vascular conduits. For xylem-mediated movement, nucleocapsids colonize metabolically active immature xylem precursor cells or xylem parenchyma, where replication and envelopment occur; subsequent programmed cell death and autolysis then release assembled virions into the hollow vessel lumen for upward transport in the transpiration stream. For phloem-dependent movement, virions assembled in companion cells may be loaded into sieve elements through dilated pore-plasmodesmal units, or nucleocapsids may invade undifferentiated sieve element precursors before maturation, with the abundant membrane-enclosed virion bundles in sieve elements favoring in situ envelopment. The envelope may also protect nucleocapsids from hydrolytic enzymes abundant in vascular sap, mirroring the reliance of many positive-sense RNA viruses on intact coat proteins for stable phloem transport. The model does not exclude nucleocapsids as a less-efficient alternative—M or G deletion mutants of the nucleorhabdovirus sonchus yellow net virus retain limited systemic infectivity at roughly 9 to 14 percent of wild-type levels—but the complete block in TYMaV-ΔM:RFP underscores the importance of mature virions. The findings carry implications beyond the plant as well: because hemipteran vectors feed on both phloem and xylem sap, and successful insect acquisition requires intact virions whose surface glycoprotein mediates entry into midgut cells, virions resident in both conduits may provide dual sources for transmission between plants.

Subject of Research: Vascular long-distance movement mechanisms of enveloped plant rhabdoviruses

Article Title: Potential contribution of enveloped virions to long-distance movement of plant rhabdoviruses

Article References: Yang, G., Deng, Y., Liu, Q., Lin, W., Wang, J., Xie, L., & Li, Z. (2026). Potential contribution of enveloped virions to long-distance movement of plant rhabdoviruses. Frontiers in Microbiology, 17, Article 1994490. https://doi.org/10.3389/fmicb.2026.1994490

Image Credits: AI Generated

DOI: 10.3389/fmicb.2026.1994490

Keywords: plant rhabdoviruses, enveloped virions, xylem, phloem, sieve elements, vessel elements, rice stripe mosaic virus, tomato yellow mottle-associated virus, matrix protein, systemic movement, transmission electron microscopy, reverse genetics

Andrey B. Shatrov and Elena V. Soldatenko of the Zoological Institute of the Russian Academy of Sciences in St. Petersburg captured a single adult female water spider in the Panika River in Russia’s Volgograd province in June 2023 and kept her in a small laboratory vial. Because the container lacked sticks or plant stems, the spider never built a diving bell or egg cocoon. Instead, she periodically produced capturing webs that stretched across the entire width of the vial—webs the researchers could then harvest and analyze. The team examined the threads with light microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), a combination rarely applied to spider silk and almost never to silk from mites.

The results were striking. Based on diameter and internal organization, the water spider’s silk fell into five distinct thread types, labeled a through e, freely interlaced in the bundles the researchers collected. All types shared basic properties: they were infinitely long, unbranched, round in cross-section, uniform in width along their entire course, and only rarely ruptured. But beyond that common ground, each type told its own structural story.

The a-type threads, mostly straight and up to 1,000 nanometers in diameter, proved the most architecturally elaborate. Under TEM, each consisted of a fibrillary wall—up to three nearly identical layers separated by narrow clear spaces—enveloping an electron-dense, vacuolated core. Fine fibers sometimes rose vertically from the wall’s outer surface, a feature the authors suggest may contribute to adhesion. Remarkably, the core could occasionally be absent altogether, and in some specimens the wall itself was lost, leaving only the core substance wrapped in a slightly wrinkled double membrane. These threads most likely correspond to dragline silk, the structural backbone spiders use for support and safety lines.

The b-, c-, and d-type threads were organized in a nearly identical, much simpler fashion: fine granular, electron-light material enveloped by a fine membrane, with tightly packed longitudinal fibrils faintly visible inside. Their diameters ranged from a maximum of about 500 nanometers in the b-type, down to roughly 120 nanometers in the c-type, to around 50 nanometers in the d-type. These threads were more convoluted and far more numerous than the a-type, and they tended to cluster in groups, with thin c-type threads sometimes running tightly alongside thicker b- or a-type fibers. The researchers interpret these fine threads as piriform silk—the attachment silk spiders use to anchor their webs to surfaces—supported by an amorphous organic film in the samples that likely represents piriform adhesive cement.

The rarest and largest threads, the e-type, measured an impressive 3.5 to 4.5 micrometers across and displayed a layered membranous wall surrounding a uniformly dense core. Their scarcity and bulk suggest a general constructive role, comparable to the thick dragline threads of orb-weaving spiders such as Nephila, whose microfibrillar walls cross at angles and can slide along one another. Unlike the a-type, the e-type surface bore no loosely packed vertical fibers.

To put the water spider’s silk in evolutionary context, the team compared it with silk from two very different mites. The water mites Limnochares aquatica and Limnesia maculata, which produce silk from dermal glands—an acquisition their freshwater ancestors evolved roughly 235 million years ago—spin threads of only one type, closely matching the a-type threads of the water spider, though larger at 1 to 3 micrometers in diameter. Like the spider’s a-type threads, the mite threads feature fibrillary walls with vertically rising surface fibers, and empty threads collapse flat against substrates in SEM, resembling elastic ribbons. In contrast, the terrestrial two-spotted spider mite Tetranychus urticae, a notorious agricultural pest, produces silk of a single type that closely corresponds to the water spider’s d-type threads: uniformly round, extremely thin at 50 to 100 nanometers, and built from fine tightly packed fibers within a moderately dense matrix.

The convergence is remarkable. Water mites, spider mites, and spiders belong to distinct phylogenetic lineages of arachnids, yet their silk-producing mechanisms yield strikingly similar thread architectures. The authors conclude that the spectrum of ways arachnids can pack silk proteins into threads is limited to a small number of possible variations, so evolution has repeatedly arrived at the same solutions. Shared aquatic environments may further drive similarity in silk formation and morphology, as seen in the match between water spider and water mite threads. Meanwhile, the water spider’s d-type-like silk echoes that of an aerial mite, hinting at the breadth of its adaptations to different conditions.

The comparison also highlights what makes spider silk special. Unlike spiders, which maintain several kinds of abdominal silk glands and up to six silk types, other arthropod groups—insects, crustaceans, pseudoscorpions, and mites—typically possess only one type of silk gland serving a specific local function. Intriguingly, the silk glands themselves differ fundamentally in origin: they are abdominal in the water spider and water mites but prosomal in tetranychid mites, meaning the same thread designs emerged from anatomically unrelated organs. Even caddisfly larvae, which spin silk underwater like the diving bell spider, produce composite paired fibers embedded in glue proteins with polysaccharide components—a substantially different construction despite similar ecological demands.

The study also fills a methodological gap. While silk research has embraced sophisticated techniques ranging from X-ray diffraction to AFM tomography, TEM has been applied only sporadically to silk threads. By fixing silk bundles in glutaraldehyde and osmium tetroxide, embedding them in araldite, and cutting ultrathin sections, the researchers could resolve internal structures invisible to surface-imaging methods—including the layered walls, vacuolated cores, and membrane-wrapped core substances that distinguish the thread types. The work suggests that the nanofibers of the external wall may provide both adhesive properties and extensibility, while the internal core may contain coiled protein fibers responsible for tensile strength, though the authors note that fully characterizing these features will require more advanced approaches. For now, the diving bell spider’s underwater web stands revealed as one of nature’s most intricate silk constructions—a five-thread toolkit spun in silence beneath the water’s surface.

Subject of Research: Ultrastructure of silk threads of the water spider Argyroneta aquatica compared with silk of water mites and spider mites

Article Title: Ultrastructure of silk threads of the water spider Argyroneta aquatica (Clerck, 1757) (Araneae, Cybeidae) in comparison with that of some mites

Article References: Shatrov, A. B., & Soldatenko, E. V. (2024). Ultrastructure of silk threads of the water spider Argyroneta aquatica (Clerck, 1757) (Araneae, Cybeidae) in comparison with that of some mites. Frontiers in Arachnid Science, 3, Article 1384553. https://doi.org/10.3389/frchs.2024.1384553

Image Credits: AI Generated

DOI: 10.3389/frchs.2024.1384553

Keywords: water spider, Argyroneta aquatica, silk ultrastructure, transmission electron microscopy, water mites, spider mites, Tetranychus urticae, piriform silk, dragline silk, arachnid evolution, diving bell, nanofibrils

The research, conducted by Julie Warner Pier of Magris Talc, addresses a fundamental challenge in mineral analysis. Amphiboles and serpentine minerals, the two mineral groups that include asbestos varieties, most often occur in nature without any asbestiform component. Amphiboles alone are estimated to make up 5 to 10 percent of the Earth’s crust and are found ubiquitously in U.S. soils. Only under specific geologic circumstances do these minerals develop the asbestiform habit — the characteristic fibrous growth pattern that makes them hazardous. When such minerals are ground into powders, all amphiboles produce elongate particles, making it extremely difficult to distinguish harmless cleavage fragments from genuinely dangerous asbestos fibers.

This distinction matters enormously for public health. Non-asbestiform amphibole and serpentine minerals have not been shown to cause asbestos-related diseases, and the Occupational Safety and Health Administration officially recognized in 1992 that non-asbestiform amphiboles should not be regulated as asbestos. Yet conventional analytical methods, particularly those relying on transmission electron microscopy (TEM), focus on the finest particles in a sample. These smallest fragments may lack the telltale morphological features of asbestos — bundles of fibers, extreme aspect ratios, and characteristic curvature — leading to inconclusive or misleading results. The ISO TEM method 10312 itself acknowledges that it cannot discriminate between individual asbestos fibers and elongate fragments from non-asbestos analogues of the same amphibole mineral.

Pier’s approach inverts this logic entirely. The key insight is rooted in a well-known principle of comminution — the science of grinding materials. When a mixture of minerals with different hardness and toughness is ground together, the softer, more friable particles break down preferentially while harder, more resistant minerals remain coarse. Asbestos, with its famously high tensile strength, resists grinding far better than talc, which is the softest mineral known with a Mohs hardness of just 1. This means that even after aggressive milling, asbestos particles preferentially survive in the coarser fraction of the powder — and it is precisely these larger particles that display the classic morphological signatures of the asbestiform habit.

To test this hypothesis, Pier developed a spiking procedure that simulates real-world mineral production. Three types of asbestos — Lone Pine tremolite, Health and Safety Laboratory (HSL) chrysotile, and short-fiber Calidria chrysotile — were carefully weighed and mixed into a coarsely crushed hydrothermal talc from the Guangxi region of China at concentrations of 500 parts per million and 100 parts per million. The mixtures were then subjected to 30 minutes of aggressive wet grinding in a McCrone micronizing mill, a vibratory mill with 48 agate cylindrical media powerful enough to reduce optical glass from 285 micrometers to 5 micrometers in just 10 minutes. This grinding far exceeds what commercial talc products typically undergo, ensuring the test conditions were at least as harsh as any industrial process.

The ground mixtures were then washed through a 400-mesh sieve — with openings of just 37 micrometers — using isopropyl alcohol and deionized water. This wet-sieving step serves a dual purpose: it concentrates the coarser particles and washes away fine material that would otherwise coat the larger particles and interfere with analysis. The retained residue was then examined by both scanning electron microscopy (SEM) and polarizing light microscopy (PLM). Remarkably, despite the brutal grinding, classic asbestiform features were clearly visible in all samples. Fiber bundles, long thin fibers with high aspect ratios, and characteristic curvature — the definitive hallmarks of asbestos — were readily detected by both techniques at both concentrations.

Perhaps most striking was the performance of PLM, which many had assumed would be inadequate for detecting chrysotile due to the thin dimensions of individual fibrils. Using a dispersion staining technique at 100× magnification, followed by confirmation at 400×, Pier found that chrysotile bundles were not only detectable but prevalent in the coarse fraction. The dispersion staining colors — magenta and blue for chrysotile in a 1.55 refractive index liquid, yellow for amphibole in 1.605 liquid — provided clear chemical differentiation from talc, which displays pale blue colors in both liquids. Even the fine, short-fiber Calidria chrysotile, previously thought to be beyond the reach of optical microscopy, was successfully identified.

The true proof of concept came from a production-scale ultrafine milled talc sample obtained from an external mining source. This material had been ground to a median particle size of just 1.5 micrometers — far finer than the 37-micrometer sieve openings — yet when 100 grams of the sample were passed through the 400-mesh sieve, a measurable retention was obtained. Within this coarse fraction, tremolite asbestos particles were detected at surprisingly low magnifications, even by stereomicroscopy at approximately 60×. The fibers displayed classic asbestiform morphology with bundles, high aspect ratios, and curvature. Meanwhile, TEM analysis of the finer particles from the same sample showed mostly shorter, parallel-sided fragments consistent with the non-asbestiform component, with none of the extremely long fibers seen by SEM appearing in the TEM preparations.

The implications for regulatory testing and consumer safety are significant. Current methods that rely solely on TEM of the finest particles may systematically miss the very particles that carry the most diagnostic information about whether a mineral is truly asbestiform. The study also notes that theoretical calculations suggest PLM may actually be more sensitive than conventional TEM on a fibers-per-gram basis for bulk materials, since typical PLM preparations analyze approximately 5 milligrams of material — roughly 50,000 times more than the 0.1 micrograms typically analyzed by TEM. With the concentrating effect of wet sieving, this sensitivity advantage is further amplified.

The technique offers a practical, accessible pathway for laboratories seeking to determine whether ground mineral products contain asbestos. Rather than requiring expensive TEM infrastructure and grappling with the ambiguities of analyzing particles too small to display diagnostic morphology, analysts can isolate the coarse fraction with simple sieving equipment and apply well-established SEM and PLM methods. The absence of bundles and curved, high-aspect-ratio fibers in the coarse fraction would indicate that a sample is non-asbestiform within the detection limits of the method. As debates over asbestos contamination in consumer products continue, this inverted analytical strategy — looking big instead of small — may prove to be the decisive tool for protecting public health.

Subject of Research: Detection of asbestiform morphology in ground mineral powders using wet-sieve concentration with SEM and polarizing light microscopy

Article Title: Morphological characteristics of asbestos in ground bulk mineral powders

Article References: Pier, J. W. (2025). Morphological characteristics of asbestos in ground bulk mineral powders. Frontiers in Geochemistry, 3, Article 1601288. https://doi.org/10.3389/fgeoc.2025.1601288

Image Credits: AI Generated

DOI: 10.3389/fgeoc.2025.1601288

Keywords: asbestos, talc, mineral powders, wet sieving, scanning electron microscopy, polarizing light microscopy, transmission electron microscopy, asbestiform morphology, amphibole, chrysotile, particle size distribution, public health

The research, led by Andreas Bezold, an adjunct assistant professor of materials science and engineering at Ohio State, focused on a pair of model alloys: a cobalt-nickel-based superalloy and a cobalt-chromium-tungsten alloy. Both belong to a class of materials prized for their ability to retain mechanical integrity at elevated temperatures, making them candidates for demanding structural roles. Rather than avoiding deformation, the researchers embraced it. In a two-step process, they first deformed the metal crystals in a controlled manner and then applied heat to slowly age the material. This combination coaxed the microscopic defects generated during deformation into atomically thin, densely packed features embedded within the crystal structure.

What emerged from this treatment was remarkable. The defects organized themselves into what the researchers describe as ordered two-dimensional defect phases: layered arrangements of structural faults enriched within the alloy. Because these features are only an atomic scale thick but spread through the material in dense networks, they act as formidable obstacles to the mechanisms that normally allow metals to deform. When stress is applied, dislocations, the tiny line defects that carry plastic deformation through a crystal, must navigate around or through these engineered barriers. The more densely and intelligently those barriers are arranged, the more force is required to distort the metal, and the stronger the alloy becomes.

The team verified this mechanism using a powerful combination of experimental and computational techniques. Transmission electron microscopy allowed the researchers to image the defect structures directly at atomic resolution, while computer simulations helped them understand how the atoms were arranged around the structural faults and how those arrangements translated into macroscopic strength. The analysis revealed that the boost in strength was intimately linked to the local atomic configuration surrounding the defects. In other words, it was not simply the presence of the faults that mattered, but their precise structure and chemistry. Altering this complex formation could directly influence how strong the resulting material would be.

The performance gains were significant on two fronts. The treated alloys could withstand markedly greater stress before deforming, and they also showed improved resistance to gradual warping at high temperatures, a degradation mode known to engineers as creep. Creep is the slow, cumulative deformation that occurs when metals are held under load for long periods at elevated temperature, and it is one of the principal factors limiting the lifespan of turbine blades, power plant components, and other hot-section hardware. By addressing both strength and creep resistance simultaneously, the defect-engineering approach targets the very properties that constrain the design of high-temperature machinery.

Importantly, the method achieves these gains without changing the chemical composition of the alloys. Conventional alloy design typically relies on adjusting elemental recipes, adding solutes or precipitates to tune properties, but every compositional change can introduce trade-offs in cost, processability, corrosion resistance, or density. The new approach instead works through the material’s internal architecture, arranging atoms via engineered defects while leaving the ingredient list untouched. Bezold noted that defects are very important to learn more about, because understanding how they interact with a material’s internal structure helps scientists design stronger materials. The team’s goal, he said, was to make these strengthening structures a deliberate part of the material’s design, and it was fascinating to see how defects could have such a positive effect on the overall durability of the alloys.

The work builds on earlier Ohio State research showing that microscopic defects formed during deformation can be converted into layers that strengthen a material’s structure. What distinguishes the new study is scale and density. The researchers report that theirs is the first approach to introduce defect densities that fully enrich the alloys, saturating the material with ordered strengthening features rather than producing isolated or sparse ones. That saturation is what allows the defects to act as a genuine design layer, a three-dimensional internal framework that complements, rather than replaces, conventional materials design strategies such as compositional tuning and heat treatment.

Michael Mills, co-author of the study and a professor of materials science and engineering at Ohio State, described the atomic-scale observations as quite stunning. Despite being associated with damage, he explained, the right defects with the right structure and chemistry can actually make a material stronger. That paradox captures the essence of the discovery: the same lattice disruptions that cause failure when uncontrolled can be harnessed to resist failure when deliberately organized. It is a conceptual shift with echoes across materials science, where researchers increasingly treat a material’s internal microstructure, down to individual atomic arrangements, as a programmable variable rather than a fixed consequence of processing.

The practical implications reach toward technologies that must survive brutal thermal and mechanical environments. High-strength alloys engineered with dense defect networks could extend the operating envelopes of aircraft turbine engines, allowing them to run hotter and more efficiently, or improve the longevity of power plant machinery subjected to sustained loads at high temperature. Longer-lasting structural materials also carry sustainability benefits, since components that resist warping and failure need to be replaced less frequently, reducing resource consumption and waste over the lifetime of large engineered systems. The researchers suggest that adding a layer of engineered defects could become a standard complement to existing design principles in structural metallurgy.

For now, Bezold’s team is helping to establish richer design principles for the field, and the researchers see the work as the opening of a fast-moving frontier. This is a field that is quickly becoming very exciting, Bezold said, expressing hope that the idea becomes a new lever that strengthens and pushes the limits of material engineering even further. The study was supported by Ohio State’s Center for Electron Microscopy and Analysis, the Alexander von Humboldt Foundation, the National Science Foundation, and the U.S. Department of Energy. Co-authors include Yunzhi Wang of Ohio State; Manuel Köbrich, Jan Vollhüter, Lukas Amon, Mathias Göken, Steffen Neumeier, Nicolas Karpstein, and Erdmann Spiecker of the University of Erlangen-Nuremberg in Germany; and Longsheng Feng of Lawrence Livermore National Laboratory in California. As the technique matures, the humble crystal defect, once the villain of materials engineering, may become its most valuable ally.

Subject of Research: Defect engineering in metal alloys to enhance strength and creep resistance

Article Title: Enhancing hidden defects to strengthen metal materials

Article References: Enhancing hidden defects to strengthen metal materials. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: materials science, metal alloys, crystal defects, superalloys, transmission electron microscopy, creep resistance, structural materials, cobalt-nickel alloy, cobalt-chromium-tungsten alloy, high-temperature materials, Ohio State University, Science journal

The story began in 2013, when researchers collecting whole plants of Nervilia nipponica, a partially mycoheterotrophic orchid distributed in Japan and Korea, noticed that its root cells were stuffed with fungal coils known as pelotons. Orchids famously depend on fungi to germinate, and many trade carbon with their partners, but the DNA extracted from these particular pelotons refused to match anything known. The researchers tentatively labeled the fungus “unidentified Agaricomycetes X,” or uAX, and distinguished four internal transcribed spacer sequence variants, types I through IV. Early multigene analyses showed only that the organism sat somewhere near several poorly resolved branches at the base of Agaricomycetes, the enormous class that contains most familiar mushrooms, brackets, and puffballs.

The breakthrough came from patience at the culture bench. The team sampled three orchid individuals, sliced their underground parts into longitudinal sections, and plated them on dilute nutrient medium at refrigerator temperatures. Only material from the base of a single inflorescence yielded viable hyphae, but from that tissue two pure culture strains were established, now deposited in Japan’s National Agriculture and Food Research Organization gene bank as MAFF425704 and MAFF425705. Sequencing of the ribosomal internal transcribed spacer and 28S genes confirmed that both isolates matched uAX type I with complete identity, finally giving the mystery lineage a living, growable representative that could be interrogated with every tool in the mycological arsenal.

With living material in hand, the researchers deployed transmission electron microscopy, the technique that has historically underpinned classification in Basidiomycota. Basidiomycete hyphae are separated by a distinctive structure called a dolipore septum, a barrel-shaped swelling around a central pore that is often surmounted by a cap. The architecture of this septal pore cap, whether it is continuous, perforated by openings, or absent altogether, has long served as a fingerprint for distinguishing major lineages. What the electron microscope revealed in Reflexicalyptra was unlike anything previously documented: a multi-pored, perforate cap whose outer margins bend outward, or reflex, away from the septum itself. Perforated caps are known from only a handful of Agaricomycetes orders, and imperforate caps characterize its closest relatives, but this reflexed configuration had never been reported anywhere in the phylum. The perforations themselves, roughly 300 nanometers across, are unusually large, and the cap is built from three layers: two electron-dense outer lines enclosing a less dense inner band. The researchers even reconstructed the cap in three dimensions from serial sections, sculpting a physical model from paper clay to visualize its geometry.

Molecular evidence reinforced what the ultrastructure suggested. The team assembled a four-locus dataset combining nuclear 5.8S and 28S ribosomal DNA with two protein-coding genes, translation elongation factor 1-alpha and the second largest subunit of RNA polymerase II, sampling representatives of every recognized Basidiomycota order. Maximum likelihood and Bayesian analyses agreed on the central conclusion: uAX forms a strongly supported, monophyletic clade that diverges early within Agaricomycetes and belongs to no existing order. Its closest relative is Tremellodendropsidales, an enigmatic clade of coral-like fungi, and together these two groups sit sister to Trechisporales and Sistotremastrales. The magnitude of the divergence is striking. While the four uAX types share 89 to 96 percent ITS sequence similarity with one another, similarity between uAX and Tremellodendropsidales falls to a mere 63 to 76 percent, far below the 80 percent threshold conventionally used to separate fungal orders.

Perhaps the most surprising dimension of the discovery came from database mining. When the team searched public sequence repositories for matches to the uAX ITS barcodes, they found the lineage was not a Japanese rarity at all. Closely related environmental sequences, recovered from soils, leaf litter, and living roots, had been archived from sites across Europe, Africa, Central America, Estonia, and South Africa, spanning temperate and tropical biomes. Type I sequences clustered mainly in forest soils and were also detected on maize roots and the roots of a tropical tree, while type IV matched material from oak and rockrose ectomycorrhizae as well as orchid roots. This pattern suggests the group is ubiquitously distributed worldwide and probably lives primarily as a saprotroph, decomposing organic matter in soil, rather than as an obligate mycorrhizal symbiont. Its association with Nervilia nipponica may be one opportunistic interaction among many, which raises a tantalizing question: if a distinct fungal order sits in common soils across the globe, why did it take an orchid in Japan to reveal it?

The answer, the authors argue, lies in the enduring gap between sequencing and taxonomy. High-throughput environmental sequencing routinely surfaces dozens of novel lineages, and one global soil study uncovered more than 40 potential new groups at or above the order level. But the International Code of Nomenclature for algae, fungi, and plants demands physical specimens from which morphological characters can be discerned before a new taxon can be formally published. Without cultures, these dark taxa remain nameless. Reflexicalyptrales breaks that pattern because the researchers secured the two things so many lineages lack: living isolates and fixed, cryopreserved type material. That combination allowed morphology, physiology, and phylogeny to be documented together, satisfying the formal requirements for naming an order, family, genus, and species in a single paper.

The cultures also yielded physiological and behavioral quirks that flesh out the portrait of this new lineage. Both strains grew best at 25 degrees Celsius, tolerated a range from 10 to 30 degrees, and stopped growing altogether at 5 and 35 degrees, a profile consistent with the temperate-to-tropical distribution inferred from environmental sequences. The hyphae are mostly binucleate, lack clamp connections, and measure just 1.5 to 4 micrometers in diameter. Attempts to induce mushroom-like fruiting bodies failed, but the fungus instead produced more than fifty sclerotia-like structures per dish on sawdust media, hard brown lumps coated in flower-like druse crystals. Given that analogous structures in other fungi, from the wood-rotting Trichaptum abietinum to the plant pathogen Sclerotinia sclerotiorum, are composed of calcium oxalate, the authors suspect Reflexicalyptra secretes similar crystals, although any ecological advantage remains unknown.

The formal taxonomy introduced in the paper is substantial. The order Reflexicalyptrales contains the family Reflexicalyptraceae and the genus Reflexicalyptra, whose name fuses the Latin for reflexed with calyptra, or cap, a direct nod to the ultrastructure that sets the lineage apart. The type species, Reflexicalyptra japonica, honors its Japanese origin and is anchored by a holotype culture cryopreserved in a metabolically inactive state. Because physical specimens are still lacking for types II through IV, the genus is conservatively defined to embrace all four clades, though the ITS phylogeny hints that the lineage may prove species-rich as more material is collected. For now, the discovery stands as both a milestone and a reminder: even well-studied soils beneath familiar forests can conceal whole branches of the fungal tree of life, waiting for someone to culture them, section them, and finally look closely enough to see what the DNA has been saying all along.

Subject of Research: Discovery and taxonomic description of a new Basidiomycota fungal order from orchid mycorrhizae

Article Title: Reflexicalyptrales ordo nov., a distinct Agaricomycetes lineage discovered from orchid mycorrhizae

Article References: Kinoshita, A., Fujimori, S., Seto, K., Ogura-Tsujita, Y., Maeda, A., Gale, S. W., Abe, J. P., Degawa, Y., & Yukawa, T. (2026). Reflexicalyptrales ordo nov., a distinct Agaricomycetes lineage discovered from orchid mycorrhizae. IMA Fungus, 17, Article e201939. https://doi.org/10.3897/imafungus.17.201939

Image Credits: AI Generated

DOI: 10.3897/imafungus.17.201939

Keywords: mycology, fungi, Reflexicalyptrales, orchid mycorrhiza, dark taxa, Basidiomycota, phylogenetics, transmission electron microscopy, septal pore cap, Nervilia nipponica, fungal taxonomy, environmental DNA

Multi principal element alloys, often called medium- or high-entropy alloys depending on their configurational disorder, have attracted growing attention in the superconductivity community over the past decade. Because their superconducting properties emerge from a blended average of several elements, researchers can tune critical temperatures, critical fields, and current-carrying capacity by adjusting composition in ways that are impossible in conventional single-element or binary superconductors. Recent reviews of body-centred cubic high-entropy alloy superconductors have highlighted their potential for high critical current densities, and individual studies of systems such as Ta–Nb–Hf–Zr–Ti and NbScTiZr have established that chemical complexity and superconductivity can coexist productively. The new study pushes this idea further by asking a subtler question: not just what elements to mix, but how to distribute them among the phases that form during solidification.

The researchers prepared three distinct alloy configurations from the same four elements, each with the same overall ratio of major to minor constituents but with the elements grouped differently. In the first configuration, niobium, zirconium, and platinum occupied the majority sublattice while titanium filled the minority share, written as (Nb, Zr, Pt)67Ti33. In the second, niobium and zirconium formed the majority group with titanium and platinum as the minority pair, (Nb, Zr)67(Ti, Pt)33. In the third, niobium alone dominated the majority fraction while titanium, zirconium, and platinum shared the remainder, Nb67(Ti, Zr, Pt)33. All three alloys solidified with a primary body-centred cubic matrix, but embedded within that matrix were eutectic regions, the fine-scale two-phase structures that form when a liquid transforms into two solid phases simultaneously at a characteristic composition and temperature.

Identifying exactly which phases reside inside those eutectic zones is a formidable analytical challenge, because the regions are small and chemically intertwined. The team turned to transmission electron microscopy-based orientation mapping, a technique that uses the diffraction patterns formed by electrons passing through an ultrathin sample to determine the crystal structure and crystallographic orientation of each region with nanometre-scale resolution. This allowed the researchers to distinguish the phases coexisting within the eutectic areas and to map how their abundance and distribution changed from one alloy configuration to another. Such microstructural detail matters enormously for superconductors, because the interfaces between phases, the boundaries between grains, and the defects scattered through the lattice all influence how magnetic flux lines move through the material when it carries current.

With the microstructures characterized, the team measured superconducting properties using a magnetic property measurement system, which tracks how a sample magnetizes and demagnetizes in response to applied magnetic fields at cryogenic temperatures. The critical temperature, at which superconductivity first appears, was determined from the onset of the susceptibility–temperature plot. The three configurations produced clearly different results. The (Nb, Zr, Pt)67Ti33 alloy showed the highest critical temperature at 8.3 kelvin, followed by (Nb, Zr)67(Ti, Pt)33 at 8.03 kelvin and Nb67(Ti, Zr, Pt)33 at 7.73 kelvin. Although the spread is less than a kelvin, in the world of applied superconductivity such systematic shifts are significant, because they demonstrate that rearranging the same four elements can reliably raise or lower the superconducting transition.

The more consequential measurement concerned the critical current density, the maximum current a superconductor can carry before resistance reappears. This quantity was evaluated through Bean’s critical state model, a standard framework that extracts current-carrying capacity from the width of magnetization–applied field loops. At applied fields above 2 tesla, the critical current density followed the same ranking as the critical temperature, with the (Nb, Zr, Pt)67Ti33 configuration leading the field. This is the regime that matters most for applications such as magnets, where superconductors must maintain large currents in intense magnetic fields. The consistency of the trend across two independent superconducting metrics strengthens the conclusion that alloy configuration, not random variation, drives the differences.

To understand why one configuration outperformed the others, the researchers analysed the flux pinning mechanisms operating in each alloy. In type II superconductors, magnetic flux penetrates as quantized vortices, and only when those vortices are anchored, or pinned, to defects can the material carry substantial current without dissipation. The team found that surface pinning dominated across all three alloys, with grain boundaries, dislocation tangles, alpha-titanium precipitates, and the PtZr intermetallic phase all acting as pinning centres. The decisive difference lay in the additional contribution from PtZr in the best-performing alloy. In the (Nb, Zr, Pt)67Ti33 configuration, the PtZr phase provided extra pinning sites that boosted the critical current density at fields above 2 tesla, on top of the contributions from the other defects.

In the other two configurations, flux pinning was driven mainly by alpha-titanium precipitates located within the eutectic phase regions, without the supplementary benefit of PtZr pinning. This contrast revealed the central finding of the study: the fraction of eutectic phase regions in the microstructure, which itself changed with the alloy configuration, governs the critical current density. Eutectic regions are rich in internal interfaces and fine precipitates, making them natural pinning landscapes. By choosing how the elements are partitioned between the majority and minority sublattices, metallurgists can control how much eutectic forms, and therefore how many pinning sites the final material contains. The work echoes a long tradition in applied superconductivity, notably the microstructure control of high-titanium NbTi alloys pioneered in the late 1980s, but extends it into the chemically far more complex multi principal element regime.

The implications reach beyond this particular alloy system. Practical superconductors for MRI machines, particle accelerator magnets, and fusion devices must combine a usable critical temperature with high critical current density under strong fields, and every incremental improvement reduces cost and engineering difficulty. The demonstration that eutectic phase engineering can systematically tune both properties in a multi principal element alloy suggests a design roadmap: rather than treating chemical complexity as a complication to be minimized, researchers can exploit it, using solidification pathways and alloy configuration as tools to sculpt the defect landscape that pins flux. The finding also connects to broader themes in the field, including recent reports of thermal-processing-driven enhancements in high-entropy alloy superconductors and the role of spin-orbit coupling in platinum-containing superconducting heterostructures.

There remain substantial hurdles before such alloys could compete with established niobium-based conductors, including the cost of platinum, the challenges of scaling production, and the need to fabricate wires rather than bulk samples. Nevertheless, the study provides a clear and quantitatively grounded demonstration that in multi principal element superconductors, the microstructure is not a byproduct of composition but an active design variable. By pairing nanoscale orientation mapping with magnetization measurements and classical pinning analysis, the IIT Delhi and NIMS team has shown that the same four elements, arranged differently, deliver measurably different superconductors. For a field searching for new ways to push current-carrying capacity upward, that is a result worth pinning down.

Subject of Research: Eutectic phase engineering of superconducting Nb–Zr–Pt–Ti multi principal element alloys

Article Title: Eutectic phase driven superconducting performance of Nb–Zr–Pt–Ti multi principal elemental alloy system with different configurations

Article References: Srivastava, N., Singh, A., Banno, N., & Santra, S. (2026). Eutectic phase driven superconducting performance of Nb–Zr–Pt–Ti multi principal elemental alloy system with different configurations. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13915-1

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13915-1

Keywords: superconductivity, multi principal element alloys, high-entropy alloys, eutectic phase, flux pinning, critical current density, critical temperature, niobium alloys, transmission electron microscopy, NbTi, magnetization, materials science

The team, led by Claudia Lago Durán, M. Andrea Molina Torres, Valeria Pfaffen, and Natalia L. Pacioni, worked within the Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC-CONICET) and the university’s Faculty of Chemical Sciences. Their starting point was a known but under-exploited chemistry: the formation of gold nanoparticles from gold(III) ions in alkaline aqueous medium, where hydroxide ions rather than an added chemical reductant drive the transformation. By systematically mapping how the key reaction variables interact, they arrived at a recipe that delivers concentrated, predominantly spherical particles of roughly 19 nanometers with remarkably tight reproducibility between batches.

To understand why this matters, it helps to recall how gold nanoparticles are usually made. The dominant approach for more than seventy years has been the Turkevich method, first published in 1951, in which citrate reduces chloroauric acid in boiling water while simultaneously acting as a capping agent that stabilizes the growing particles. It is elegant and simple, but it embeds a tension: the same molecule both reduces and stabilizes, and subtle shifts in pH, citrate protonation, temperature, and mixing can swing the outcome from a clean monodisperse colloid to a polydisperse mixture of spheres, plates, and aggregates. Studies as recent as 2018 have shown that even slight pH fluctuations during citrate synthesis measurably alter the performance of the resulting particles in sensing applications.

For applications that demand a clean surface, researchers have long sought so-called naked nanoparticles, particles free of citrate or other stabilizing ligands, whose surfaces can be functionalized precisely with the chemistry of choice. Photochemical routes and other reductant-free strategies have been explored, but they often trade cleanliness for complexity, requiring specialized equipment or yielding dilute, poorly controlled colloids. The Córdoba group’s approach is deliberately minimalist: gold(III) precursor, sodium hydroxide, water, heat, and stirring, nothing else. The alkaline medium converts gold(III) into hydroxo species that appear to undergo self-reduction and growth under the reaction conditions, producing particles whose surfaces carry no foreign capping molecules.

The real innovation, however, lies not in the chemistry itself but in how the team optimized it. Rather than adjusting one variable at a time, the traditional and inefficient approach, they employed a Box–Behnken design, a response surface methodology from the design of experiments (DoE) toolkit. This statistical framework allows researchers to explore a multidimensional parameter space efficiently, fitting a mathematical model that captures not only the main effects of each variable but also the interactions between them. The team investigated four factors: the concentration of Au(III), the concentration of sodium hydroxide, the stirring rate, and the temperature, monitoring the outcome through ultraviolet-visible absorbance and the plasmon-related response parameter Ψ.

The model revealed something that one-variable-at-a-time experimentation would almost certainly have missed: the significant drivers of nanoparticle formation were not just the individual concentrations of gold and hydroxide, but the interactions of NaOH concentration with both stirring rate and temperature. In other words, the effect of hydroxide depends on how fast the solution is mixed and how hot it is, a coupling that reflects the delicate balance between nucleation, growth, and stabilization in the forming colloid. Complementary control experiments reinforced the picture, confirming that the alkaline medium is essential for particle formation and that temperature governs the rate at which the nanoparticles appear.

Armed with the fitted model, the researchers applied a desirability function, a standard DoE technique that combines multiple response goals into a single optimization target. Here the goals were twofold: maximize the concentration of nanoparticles produced while minimizing polydispersity, the spread of particle sizes that degrades performance in sensing and imaging. The optimization converged on a precise set of conditions: 200 micromolar Au(III), 4.75 millimolar NaOH, a temperature of 130 degrees Celsius, and a stirring rate of 350 revolutions per minute. When the team ran the synthesis under these conditions, the resulting colloid showed excellent reproducibility from batch to batch, the central goal of the entire exercise.

Characterization confirmed the quality of the product. Transmission electron microscopy showed predominantly spherical particles with a mean diameter of 18.66 nanometers and a standard deviation of 4.78 nanometers, indicating a reasonably narrow size distribution. Dynamic light scattering, which measures the particles in solution rather than dried on a grid, gave a hydrodynamic diameter of 19.8 plus or minus 0.9 nanometers with a polydispersity index of 0.208, values consistent with a stable, well-defined colloid. The close agreement between the dry and hydrodynamic sizes suggests the particles carry minimal surface decoration, exactly what one expects from naked nanoparticles stabilized only by the ionic environment of the alkaline medium.

The broader significance of the work extends beyond gold. The same group had previously demonstrated that an experimental design approach could improve batch-to-batch reproducibility in silver nanoparticle synthesis, and the new study extends that philosophy to a reductant-free gold system. As a 2022 review noted, design of experiments remains a surprisingly underused strategy in inorganic materials synthesis, where tradition and intuition often dictate protocol development. By treating synthesis as a quantifiable, modelable process rather than an art, the Córdoba team offers a template that other laboratories can adapt to their own nanomaterial systems, potentially accelerating the path from bench-scale curiosity to manufacturable product.

For the growing community working on gold nanoparticle biosensors, therapeutics, and catalysis, the message is compelling. A clean, ligand-free particle of controlled size, produced by a statistically validated protocol that any competent lab can reproduce, removes two of the biggest obstacles to translating nanogold research into real-world devices: surface contamination that complicates functionalization, and irreproducibility that undermines comparisons between studies. The work was supported by grants from Argentina’s National Agency for the Promotion of Science and Technology (ANPCyT) and the university’s Secretariat of Science and Technology, with fellowship support from CONICET. As nanomedicine and nanosensing mature, methods like this one, humble in their chemistry but rigorous in their statistics, may prove to be the quiet foundation on which reliable nanotechnology is built.

Subject of Research: Reducing-agent-free synthesis of gold nanoparticles optimized by design of experiments for batch-to-batch reproducibility

Article Title: Efficient production of gold nanoparticles without reducing agents: a strategy optimized using the design of experiments

Article References: Durán, C. L., Torres, M. A. M., Pfaffen, V., & Pacioni, N. L. (2026). Efficient production of gold nanoparticles without reducing agents: a strategy optimized using the design of experiments. Journal of Nanoparticle Research, 28(10), Article 267. https://doi.org/10.1007/s11051-026-06790-z

Image Credits: AI Generated

DOI: 10.1007/s11051-026-06790-z

Keywords: gold nanoparticles, nanoparticle synthesis, design of experiments, Box-Behnken design, chemometric optimization, reducing-agent-free synthesis, batch-to-batch reproducibility, alkaline aqueous medium, naked nanoparticles, transmission electron microscopy, dynamic light scattering, polydispersity

The problem the team set out to solve is a stubborn one in nanoscience. Over the past decade, dozens of papers have compared biologically synthesized zinc oxide nanoparticles with chemically synthesized ones, and many have reported striking differences. But in most of those studies, the biological and chemical routes differed not just in the presence of a plant or algal extract — they also used different zinc precursors at different concentrations, different pH values, different temperatures, and different reaction times. When so many parameters change at once, it becomes impossible to say whether the observed differences come from the biological extract itself or simply from the altered reaction chemistry. The Mexican team, led by J. D. A. Loa and N. G. Rojas-Avelizapa, designed their experiment to eliminate that ambiguity.

Their approach was elegantly simple. Both batches of nanoparticles were produced by alkaline precipitation under identical conditions: the same 0.3 M zinc nitrate precursor, the same pH of 10, the same room-temperature reaction, the same two-hour reaction time, the same centrifugation and washing steps, and the same drying protocol at 60 °C with no calcination. The only difference was that in the biological synthesis, 20 milliliters of an aqueous Sargassum extract — prepared by acidifying and heating the washed, dried, pulverized seaweed biomass — replaced an equivalent volume of distilled water. Any difference between the two materials could therefore be attributed to the extract and its biomolecules, rather than to confounding synthesis parameters.

The choice of Sargassum was no accident. This brown macroalga, which has become infamous for its massive blooms washing up on Caribbean and Gulf of Mexico coastlines, is rich in sulfated polysaccharides such as fucoidan and carrageenan, along with alginates and laminarin. These macromolecules carry highly electronegative sulfate and carboxylate functional groups that can bind zinc ions, initiate electrostatic nucleation, and then wrap around growing particles as templates or capping agents. In other words, the seaweed extract is not a passive additive; it is an active participant in the architecture of the resulting nanomaterial.

The optical fingerprints of the two materials diverged immediately. Under ultraviolet-visible spectroscopy, the biologically synthesized particles, which the authors call B-ZnO-NPs, showed an absorption maximum at 354 nanometers, while the chemically synthesized C-ZnO-NPs absorbed at 369 nanometers. That fifteen-nanometer blue shift is consistent with smaller particles in the biological batch, but the researchers caution that absorption in zinc oxide is also shaped by morphology, surface chemistry, crystalline quality, and defect-related electronic states. Notably, the absorption band of the chemically synthesized particles was broader and less well defined, a pattern the authors associate with lower crystal lattice quality in the absence of organic stabilizers.

Band-gap analysis using Tauc plots reinforced the picture. The biologically derived particles exhibited an apparent optical band gap of 3.24 electron volts, compared with 3.02 electron volts for the chemically derived ones. The chemical batch actually fell below the band gap of bulk zinc oxide, about 3.37 electron volts, which the researchers interpret as evidence of structural defects in the crystal lattice — vacancies and interstitials that create recombination sites for charge carriers and shift the energy levels of the material. Because the band gap determines the photon energy needed to photoactivate the semiconductor, these differences could translate directly into different photocatalytic and antimicrobial performance, although the authors emphasize that direct functional assays remain to be done.

Fluorescence spectroscopy added another layer of evidence. Excited at 365 nanometers, both materials emitted in the yellow-orange range, with maxima at 569 nanometers for the biological particles and 574 nanometers for the chemical ones. Emission in this range is not the signature of pristine, defect-free zinc oxide, which glows near 370 nanometers from direct excitonic recombination. Instead, it points to defect-mediated transitions involving oxygen interstitials, oxygen or zinc vacancies, zinc interstitials, or surface states. The slight blue shift of the biological particles’ emission may reflect surface states generated by the organic coating inherited from the Sargassum extract, which has been reported to emit between 400 and 580 nanometers in coated zinc oxide systems.

Infrared spectroscopy confirmed the formation of the zinc-oxygen bond in both materials, with characteristic bending vibrations between 400 and 575 wavenumbers, but also revealed subtle shifts suggesting increased rigidity in some zinc-oxygen double bonds. Crucially, the biological particles showed additional features in the hydroxyl and carbonyl regions consistent with organic functional groups from the seaweed interacting with the nanoparticle surface — chemical evidence of a possible bio-derived capping layer, though the authors note that techniques such as X-ray photoelectron spectroscopy and thermogravimetric analysis would be needed to confirm and quantify it.

The colloidal and morphological measurements were perhaps the most dramatic. Dynamic light scattering showed that the biological particles carried a zeta potential of −28.65 millivolts, well beyond the −14.07 millivolts of the chemical batch, indicating much stronger electrostatic repulsion between particles and therefore better colloidal stability. The polydispersity index told a similar story: 0.59 for the biological material versus 0.96 for the chemical one, the latter signaling high heterogeneity. Transmission electron microscopy then revealed why. The biologically synthesized particles were small, granular, and relatively uniform, averaging about 34 nanometers in diameter, while the chemically synthesized particles grew into larger cubic and rod-shaped structures averaging roughly 158 nanometers in length — a sign of uncontrolled nucleation and growth in the absence of stabilizing agents.

The authors are careful about the limits of their conclusions. The contribution of the Sargassum extract should be read as an integral effect, they write, because local reaction chemistry — ionic strength, viscosity, conductivity, buffering — was not measured, and the extract may influence the reaction environment in ways beyond simple surface capping. Complementary analyses, including X-ray diffraction, high-resolution electron microscopy with elemental mapping, and spectroscopic surface probes, would be needed to pin down crystallinity, defect identity, and the precise chemical nature of the organic coating. Functional assays testing photocatalytic dye degradation, antimicrobial activity, and wastewater treatment performance would then be required to connect the observed physicochemical differences to real-world applications.

Even with those caveats, the study delivers a message with broad implications. It demonstrates, under rigorously controlled conditions, that the biochemical composition of a biological precursor is not a footnote in nanoparticle synthesis — it is a design lever. Sulfated polysaccharides and other acidic biomolecules from Sargassum appear to control nucleation, modulate growth, and stabilize the surface, yielding smaller, more homogeneous, more colloidally robust particles with distinct optical properties. For a field often criticized for irreproducible green-synthesis claims, the work offers a template: hold every parameter constant, change only the biological ingredient, and measure everything. It also hints at a satisfying circularity — turning an invasive seaweed that clogs beaches into a precision tool for engineering nanomaterials whose properties can be tuned for environmental remediation, sensing, and medicine. As the authors conclude, selecting the right biological precursor and synthesis strategy may be the key to obtaining zinc oxide nanoparticles whose characteristics are tailored, rather than left to chance.

Subject of Research: Physicochemical comparison of zinc oxide nanoparticles synthesized biologically with Sargassum extract versus chemically under identical conditions

Article Title: Physicochemical comparison of zinc oxide nanoparticles obtained by biological and chemical synthesis

Article References: Loa, J. D. A., Guatemala-Cisneros, M. E., Hernández-Jiménez, M. O., & Rojas-Avelizapa, N. G. (2026). Physicochemical comparison of zinc oxide nanoparticles obtained by biological and chemical synthesis. Discover Chemistry, 3(1), Article 470. https://doi.org/10.1007/s44371-026-00922-z

Image Credits: AI Generated

DOI: 10.1007/s44371-026-00922-z

Keywords: zinc oxide nanoparticles, Sargassum, green synthesis, chemical precipitation, band gap, zeta potential, colloidal stability, transmission electron microscopy, photocatalysis, nanobiotechnology, sulfated polysaccharides, defect chemistry

The material at the heart of the study is (TiZrVCrAl)N, a nitride of a high-entropy alloy containing five metallic elements: titanium, zirconium, vanadium, chromium, and aluminum. High-entropy alloys, first articulated as a class in landmark reviews by Brian Cantor and by Daniel Miracle and Oleg Senkov, abandon the traditional idea of one dominant base metal. Instead, five or more elements are mixed in near-equal proportions, producing extreme configurational entropy that stabilizes unexpected crystalline phases. When such alloys are reacted with nitrogen, the resulting nitride films inherit this chemical complexity, and with it a combination of high hardness, thermal stability, and wear resistance that conventional binary nitrides such as TiN struggle to match.

High-entropy nitride coatings of the TiZrVCrAl family have already shown promise in demanding applications. Earlier work published in the Journal of Vacuum Science and Technology A reported that a TiZrVCrAl coating on aerospace bearings reduced the friction coefficient in oil-liquid mixed media, while magnetron-sputtered TiVZrCrAl nitride films have achieved super-hard behavior. The new study adds a critical piece to this picture by examining how these coatings form on the workhorse titanium alloy Ti-6Al-4V, the material that carries much of the structural load in modern aircraft, and by asking whether the way that alloy is processed changes the coating that grows on it.

To explore this question, the team prepared two versions of the Ti-6Al-4V substrate. One had a conventional coarse-grained structure. The other was converted to an ultrafine-grained state using severe plastic deformation, a family of processing techniques, including equal-channel angular pressing, that refines grains to sub-micrometer dimensions by imposing enormous strain without changing the shape of the part. Ultrafine-grained titanium alloys are prized for their enhanced strength, fatigue resistance, and creep performance, and previous studies by the same research groups had already shown that such substrates can improve the scratch resistance and adhesive strength of protective coatings. The new work investigates what happens at the finest structural level when a high-entropy nitride is deposited on each substrate type.

The coatings themselves were produced by vacuum arc physical vapor deposition, or arc-PVD, a technique in which an electric arc vaporizes a metallic cathode, ionizes the vapor, and accelerates the ions toward a negatively biased substrate. Arc-PVD is prized industrially because it produces dense, strongly adherent films at reasonable deposition rates. The researchers deposited two architectures on both substrate types: a monolayer coating of (TiZrVCrAl)N and a multilayer coating in which (TiZrVCrAl)N layers alternate with layers of conventional TiN. Multilayer designs are widely used to toughen hard coatings, because interfaces between layers can block dislocation motion and deflect cracks.

The first major result concerns the internal structure of the monolayer coating. Using X-ray diffraction and transmission electron microscopy, the team found that the monolayer (TiZrVCrAl)N film is not structurally uniform through its thickness. Instead, it exhibits a pronounced phase gradient. At the interface where the coating meets the titanium alloy, the film is largely amorphous, lacking long-range crystalline order. Moving toward the outer surface, the structure progressively crystallizes into a face-centered cubic lattice, the same rock-salt-type structure adopted by classical transition-metal nitrides. This gradient makes physical sense: the earliest atoms to arrive on the substrate condense onto a chemically different surface with imperfect lattice matching, so the first atomic layers cannot easily find a crystalline template. As the film thickens, however, newly arriving atoms nucleate on the already-formed crystalline material beneath them, and the face-centered cubic phase establishes itself and grows toward the surface.

The multilayer (TiZrVCrAl)N/TiN coating told a different story. Rather than a single smooth gradient, it displayed pronounced structural and chemical periodicity, with alternating regions of varying degrees of crystallinity repeating through the film thickness. This periodicity mirrors the alternating layer architecture imposed by the deposition sequence, confirming that the multilayer design is faithfully reproduced at the nanometer scale and that each layer transition resets, at least in part, the structural state of the growing film. Such periodic interfaces are precisely what multilayer coating designers intend, and their clear observation in a five-element high-entropy system is an encouraging sign that sophisticated architectures can be engineered in these chemically complex nitrides.

The most striking discovery, however, is the influence of the substrate itself. When the coating was deposited on the ultrafine-grained Ti-6Al-4V rather than the coarse-grained alloy, the coherent scattering region in the coating, the size of the domains over which the crystal lattice remains perfectly aligned, dropped from 14.0 plus or minus 0.3 nanometers to 8.2 plus or minus 0.6 nanometers. In other words, the crystalline domains in the film became roughly forty percent smaller simply because the metal underneath had a finer grain structure. The effect extended to grain morphology as well: near the substrate-coating interface, the ultrafine-grained substrate produced more equiaxed grains, meaning grains with roughly equal dimensions in all directions rather than elongated columnar shapes, and their average size was about twenty percent smaller than the corresponding grains grown on the coarse-grained substrate.

Why should the substrate grain size matter so much? The interface between a coating and its substrate is a zone of intense atomic activity during deposition. Nucleation of the first crystalline layers depends on the topography, chemistry, and defect structure of the surface, all of which differ between coarse-grained and ultrafine-grained titanium. An ultrafine-grained surface presents a far higher density of grain boundaries, which can act as preferential nucleation sites and disrupt the lateral growth of columnar grains. The result is a finer, more equiaxed initial grain structure in the coating, and that initial structure propagates its influence through the film as growth continues, reflected in the reduced coherent scattering domain size measured by diffraction. The study thus demonstrates that substrate microstructure is not a passive backdrop but an active participant in coating formation.

The practical implications are considerable. The authors connect these microstructural differences to the mechanical properties of the coatings, discussing how composition, architecture, and now substrate grain structure jointly determine performance. Smaller crystalline domains and more equiaxed grains near the interface are generally associated with higher hardness and better load-bearing capacity, following the well-established Hall-Petch-type reasoning that grain boundaries impede dislocation motion. Combined with earlier findings that ultrafine-grained titanium substrates enhance coating adhesion and scratch resistance, the new results support a coherent design strategy: process the titanium alloy into an ultrafine-grained state first, then deposit the high-entropy nitride coating, and obtain a component whose surface layer is finer, more defect-controlled, and potentially longer-lasting than anything achievable by coating alone. For aerospace components such as bearings, shafts, and fasteners, where Ti-6Al-4V must resist wear, corrosion, and fatigue simultaneously, that strategy could translate directly into longer service intervals and lighter, more efficient machines. The work also fits into a broader vision, championed by proponents of severe plastic deformation, of so-called superfunctional materials in which bulk nanostructuring and surface engineering are combined deliberately rather than by accident. As high-entropy coatings mature from laboratory curiosities into industrial workhorses, studies like this one make clear that the full performance of these remarkable films can only be unlocked by treating the substrate and the coating as a single engineered system, designed together from the grain boundaries of the metal to the outermost atomic layers of the film.

Subject of Research: Microstructure of high-entropy (TiZrVCrAl)N nitride coatings deposited on coarse-grained and ultrafine-grained Ti-6Al-4V titanium alloy

Article Title: Microstructure of high-entropy (TiZrVCrAl)N coatings deposited on Ti–6Al–4V alloy with different grain structures

Article References: Valiev, R. R., Ovchinnikov, S. V., Savina, Y. N., Belyakov, A. N., Modina, I. M., Nikolaev, A. A., Nazarov, A. Y., Ramazanov, K. N., Caron, A., & Valiev, R. Z. (2026). Microstructure of high-entropy (TiZrVCrAl)N coatings deposited on Ti–6Al–4V alloy with different grain structures. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13813-6

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13813-6

Keywords: high-entropy alloys, thin films, arc-PVD, Ti-6Al-4V, ultrafine-grained titanium, severe plastic deformation, nitride coatings, transmission electron microscopy, X-ray diffraction, coating microstructure, aerospace materials, nanocrystalline materials