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The laser-induced fabrication of nanostructures with feature sizes below the optical diffraction limit is possible for almost any material for arbitrary sample geometries and dimensions by exploiting nonlinear excitations or optical near-field interactions. This overview highlights historical milestones, explains the underlying physical processes and associated challenges, and discusses current and future trends in the field of ultrafast laser nanostructuring.
Hard and transparent glass-ceramics (GCs) from the ZnO-Al2O3-SiO2 (ZAS) system containing TiO2 as a nucleating agent often exhibit a grayish to brownish hue, limiting their use in applications requiring high transmittance and colorless materials. This coloration arises from charge-transfer mechanisms involving Ti ions. To address this issue, the oxidizing agents CeO2, Sb2O3, and As2O3 were incorporated individually into a TiO2-nucleated ZAS base composition to promote the oxidation of Ti3+ ions to Ti4+ ions, as the latter exhibits minimal coloring effects. The experimental characterization of the glasses and GCs comprised the following steps: Differential Scanning Calorimetry, to study the influence of the optical clarifiers on the thermal behavior and crystallization kinetics; UV-Vis Spectroscopy and CIELAB color analysis to evaluate the effectiveness of the oxidizers in mitigating the color; Electron Paramagnetic Resonance to determine the oxidation states of the coloring ions; Rietveld analyses to assess the impact of microstructural factors on light absorption; and Vickers microhardness to evaluate the effect of the composition and heat treatments on the mechanical performance. The results demonstrate that As2O3 and Sb2O3 are more effective than CeO2 in reducing coloration and enhancing the transmittance in the visible range of the ZAS GCs containing TiO2 without affecting their hardness.
The room temperature cyclic plastic deformation behavior of laser powder bed fused stainless steel 316L heat treated to two microstructural states was investigated after room temperature strain-controlled low-cycle fatigue tests. The lower temperature heat treatment (450 °C/4 h) retains the cellular structure present in an as-built material. In contrast, the higher temperature heat treatment (450 °C/4 h followed by 900 °C/1 h) is associated with the disappearance of the manufacturing-induced cellular structure (M − CS) whilst maintaining similar grain morphology and texture, consequently leading to decreased static yield strength. The two different microstructures were tested as a function of strain amplitude by both incremental step and single step testing to explore transferability of established knowledge from the latter to the former. This was followed by detailed electron microscopy studies to understand the cyclic deformation mechanisms. While both material conditions exhibited distinct cyclic softening after a short initial hardening phase, removing the M − CS induced a less pronounced subsequent degree of relative softening. Microstructural investigations of the M − CS-free condition revealed wavy-slip behavior with the formation of low energy dislocation structures acting as a softening agent. In the presence of M − CS associated with the lower-temperature heat-treated condition, microstructural evidence points towards planar slip behavior. While the mode of slip seems to change by the heterogeneities associated with the presence of cellular structure, the ability of this microstructural feature to act as barrier against plastic deformation when cyclically strained is degraded, which is reflected in the strong reduction of the cyclic yield strength.
This study investigates the potential of bio-admixtures derived from Sargassum Natans (SN1E, SN2E), Sargassum fluitans (SFE), water hyacinth (WHE), miscanthus grass (ME), and plantain stem (PSE) as sustainable alternatives to polycarboxylic ether (PCE) superplasticizers in cement-based materials. The research examines their effects on rheology, hydration, microstructure, and mechanical properties to assess their suitability for eco-friendly construction applications. Cement pastes and mortars incorporating 0.1% and 1% bio-admixture dosages were analyzed using isothermal calorimetry, thermogravimetric analysis (TGA/DTG), static yield stress measurements, and compressive strength testing at 7 and 28 days. Results indicate that all mixtures containing admixtures exhibited lower initial yield stress values, indicating a liquefying effect initially. At 0.1% dosage, the admixtures exhibited comparable or slightly improved compressive strength relative to the reference (REF), with no significant losses. However, at 1% dosage, PCE, WHE, ME, and PSE showed notable strength reductions, particularly ME, which significantly impaired both 7-day and 28-day strengths. Hydration studies revealed that bio-admixtures exhibited lower retardation effects compared to PCE, with SN1E, SN2E, and SFE promoting early hydration and portlandite (CH) formation. Conversely, ME and PSE exhibited delayed hydration, leading to lower early-age strengths but a more sustained hydration process over time. Thermal analysis further confirmed these trends, with bio-admixture-modified pastes maintaining stable hydration profiles, while PCE exhibited the strongest retardation effect, as evidenced by its lower total weight loss, and reduced CH content. These findings highlight the potential of bio-admixtures as sustainable modifiers in cementitious materials, providing workability benefits while minimizing hydration delay, making them promising candidates for green construction.
Objective: Iron-based contrast agents (IBCAs) have potential as alternatives to Gd-based contrast agents (GBCAs), intending to address the long-term safety concerns associated with gadolinium. We investigated [Fe-EOB-tCDTA] as a potential alternative to [Gd-EOB-DTPA]2- for liver magnetic resonance imaging (MRI).
Materials and methods: [Fe-EOB-tCDTA] was synthesized by reacting the monoanhydride of tCDTA with 4-ethoxybenzylamine followed by iron chelation. Its kinetic stability was spectrophotometrically evaluated using a zinc stress test. The T1 relaxivity was measured in water and serum at 1.41 T, 37 °C and 3 T, 23 °C. Cellular cytotoxicity against liver-derived BRL-3A cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. The uptake of [Fe-EOB-tCDTA] by liver cells was investigated using LA-ICP-MS, in competition with [Gd-EOB-DTPA]2-. T1 contrast effects in BALB/c mice were evaluated by DCE-MRI.
Results: [Fe-EOB-tCDTA] exhibited higher kinetic stability than [Fe-(tCDTA)]-and demonstrated a r1 of 1.94 and 2.45 mM-1s-1at 1.4 and 3 T in serum. No significant differences in the short-term cytotoxicity were observed between [Gd-EOB-DTPA]2-and [Fe-EOB-tCDTA]. [Fe-EOB-tCDTA] inhibited [Gd-EOB-DTPA]2- uptake in BRL-3A liver cells. [Fe-EOB-tCDTA] (0.2 mmol/kg) demonstrated a comparable blood peak RE% compared to [Gd-DO3A-butrol] (0.1 mmol/kg). However, RE of [Gd-EOB-DTPA]2- in liver at a clinical dose was significantly higher than that of [Fe-EOB-tCDTA] at both injection doses.
Conclusion: [Fe-EOB-tCDTA] provides comparable blood enhancement to [Gd-DO3A-butrol] and exhibits hepatobiliary excretion like [Gd-EOB-DTPA]2- but without a comparable liver contrast. [Fe-EOB-tCDTA] may serve as an alternative to nonspecific GBCAs, particularly for patients with renal insufficiency and a contraindication to GBCAs.
In article number e02344, Ievgen S. Donskyi, Vasile-Dan Hodoroaba, and co-workers present a straightforward correlative imaging approach for locating graphene flakes and impurities on the nanoscale within an ink as a highly complex matrix. A systematic comparison of different surface imaging methods demonstrates that the combination of time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning electron microscopy (SEM) provides the most effective strategy for visualizing and identifying these features, helping to shed light in the dark.
The sinterability of scaffolds, 3D-printed by binder jetting, and their uniaxially pressed compact counterparts made from the bioactive glasses BG 13–93 and BG F3 was investigated with heating microscopy, DTA, optical and electron microscopy, and XRD. As the 3D-printed specimens had lower initial relative densities, more shrinkage and more time to reach full densification were needed. In the case of the slow-crystallizing BG 13–93, this delay did not provoke crystallization-induced sinter retardation. For the more readily crystallizing BG F3, however, a final relative density > 95% was reached only for the particle size fraction <32 µm. For this particle size fraction, the BG 13–93 scaffolds reached bending strengths quite similar to those measured on bulk glass samples, whereas BG F3 scaffolds reached about 30% less. In vitro cell viability tests on (<32 µm)-scaffolds proved their cytocompatibility with pre-osteoblasts on both BGs.
Polystyrene (PS), a widely used commodity plastic, has a persistently low recycling rate, making it a major contributor to plastic pollution. Selective PS upcycling under ambient conditions remains challenging due to its chemically inert structure, characterized by stable C-C and C-H bonds. As a consequence, efficient PS degradation typically requires energy-intensive pyrolysis or harsh oxidizing conditions. Existing homogeneous photo catalysts, such as strong acids or metal salts, are unsustainable long-term solutions for PS waste management due to their lack of reusability and complex separation requirements. Although covalent organic frameworks (COFs) and covalent triazine frameworks (CTFs) have previously been explored as general photocatalysts, their use in selective PS upcycling remains underexplored. Here, we report an iron-doped CTF for the efficient photocatalytic upcycling of PS under ambient conditions. By harnessing the framework's porous character and tunable electronic and photophysical properties, the catalyst incorporates less than 3 wt% iron and offers a sustainable alternative to photocatalysts with higher metal content. Synthesized via solvent-free mechanochemical Friedel- Crafts alkylation of trichlorotriazine and phenothiazine, the CTF forms a porous, p-type semiconductor with FeCl4 ions cross-linking 2D CTF polymer sheets to form an [FeCl4]@CTF heterogeneous photocatalyst. The disclosed [FeCl4]@CTF photocatalyst achieves 100% degradation of commercial and post-consumer PS under ambient conditions, yielding approximately 70% of valuable aromatic compounds with high selectivity. The scalable mechanochemical synthesis of the CTF, coupled with its reduced reliance on high metal loadings provides a sustainable blueprint for organocatalyst-driven plastic waste management using earth-abundant metals.
Mg isotope fractionation during microbial dolomite formation in the Khor Al‐Adaid sabkha, Qatar
(2026)
The processes governing dolomite [CaMg(CO3)2] formation remain among the most debated topics in sedimentary geology. Although primary dolomite can precipitate at low temperatures in certain modern environments, its scarcity today contrasts sharply with its abundance in ancient rocks—a discrepancy known as the ‘dolomite problem’. Dolomite typically forms through two pathways: Primary precipitation during early diagenesis, often influenced by microbial activity and organic matter and secondary replacement of preexisting carbonates during burial at higher temperatures. In this study, we investigate Mg isotope fractionation in a modern sabkha in southern Qatar to evaluate its potential as a tracer of dolomite formation processes. We analysed δ26Mg and δ44Ca in surface- and pore waters, authigenic clays and organic- and leached dolomite- containing fractions. Ca isotopes reveal an ~1‰ fractionation between pore water–organic
Polymetallic W-(Sn), Sn-Zn±(In), and Zn-Pb±(Sn) skarns in the Schwarzenberg District of the western Erzgebirge are expressions of a polyphase mineral system that formed between >330 Ma and ~295 Ma. Due to the polyphase nature of the skarns, the physicochemical conditions of skarn formation and the actual timing of ore formation have remained poorly constrained. To better understand skarn-forming processes in the Erzgebirge, we obtained new mineral chemical data of prograde garnet from all major skarns across the Schwarzenberg District by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry. Results illustrate that the oldest generation of skarns formed under relatively fluid-buffered conditions and high fluid/rock ratios. Associated garnet has a pronounced andradite component, contains low concentrations of HFSE, Mn, and Ga and is variably enriched in Sn, W, As, and Li. Elevated concentrations of HFSE, Mn, and Ga in garnet from skarns with skarnoid textures indicate that these formed under mainly rock-buffered conditions (low fluid/rock ratios). Associated garnet is dominantly grossular and invariably low in Sn and W concentrations. The mineral chemistry of garnet from the youngest skarn bodies indicates renewed ingress of magmatic-hydrothermal fluids marked by an intermediate grandite composition, low HFSE, Al, and Ga concentrations as well as a variable enrichment of Sn and W. Although these general patterns are well defined, our data also clearly reveal considerable variability of garnet compositions on the local scale. The same is true for Sn and W concentrations in garnet of all stages. These are found to be too variable as to constitute meaningful exploration vectors. However, they are well suited to place general constraints on the physicochemical conditions of polyphase skarn formation in the Schwarzenberg District.