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Keywords = nanoscale precipitation

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19 pages, 4287 KiB  
Article
Tailoring Microstructure via Rolling to Achieve Concurrent High Strength and Thermal Conductivity in Mg-Zn-Nd-Zr Alloys
by Hailong Shi, Xiaohuan Zhang, Xin Li, Yining Zhang, Siqi Li, You Wang, Xiaojun Wang, Xiaoshi Hu, Xuejian Li, Chao Xu, Weimin Gan and Chao Ding
Materials 2025, 18(15), 3578; https://doi.org/10.3390/ma18153578 - 30 Jul 2025
Viewed by 158
Abstract
This study examined the comprehensive properties of Mg-Zn-Nd-Zr alloys in order to achieve both high strength and thermal conductivity simultaneously. The impact of rolling on the microstructure, mechanical properties, and thermal conductivity was analyzed for Mg-5Zn-xNd-0.4Zr alloys (x = 1, 2). The results [...] Read more.
This study examined the comprehensive properties of Mg-Zn-Nd-Zr alloys in order to achieve both high strength and thermal conductivity simultaneously. The impact of rolling on the microstructure, mechanical properties, and thermal conductivity was analyzed for Mg-5Zn-xNd-0.4Zr alloys (x = 1, 2). The results indicate that the addition of Nd promotes the formation of the W phase (Mg3Zn3RE2), which contributes to grain boundary strengthening and enhances the overall strength. Moreover, dynamic precipitation during the rolling process leads to the formation of nanoscale MgZn2 and Zn2Zr phases, significantly improving both the strength and thermal conductivity. After rolling, both the Mg-5Zn-1Nd-0.4Zr (ZNK510) and Mg-5Zn-2Nd-0.4Zr (ZNK520) alloys exhibited a notable enhancement in thermal conductivity, with ZNK520 demonstrating superior properties due to its higher Nd content. This study highlights that optimizing alloy composition and phase evolution through rolling can markedly enhance both the mechanical and thermal properties, offering a promising strategy for the development of high-performance magnesium alloys. Full article
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19 pages, 4569 KiB  
Article
Tailored Magnetic Fe3O4-Based Core–Shell Nanoparticles Coated with TiO2 and SiO2 via Co-Precipitation: Structure–Property Correlation for Medical Imaging Applications
by Elena Emanuela Herbei, Daniela Laura Buruiana, Alina Crina Muresan, Viorica Ghisman, Nicoleta Lucica Bogatu, Vasile Basliu, Claudiu-Ionut Vasile and Lucian Barbu-Tudoran
Diagnostics 2025, 15(15), 1912; https://doi.org/10.3390/diagnostics15151912 - 30 Jul 2025
Viewed by 167
Abstract
Background/Objectives: Magnetic nanoparticles, particularly iron oxide-based materials, such as magnetite (Fe3O4), have gained significant attention as contrast agents in medical imaging This study aimsto syntheze and characterize Fe3O4-based core–shell nanostructures, including Fe3O4 [...] Read more.
Background/Objectives: Magnetic nanoparticles, particularly iron oxide-based materials, such as magnetite (Fe3O4), have gained significant attention as contrast agents in medical imaging This study aimsto syntheze and characterize Fe3O4-based core–shell nanostructures, including Fe3O4@TiO2 and Fe3O4@SiO2, and to evaluate their potential as tunable contrast agents for diagnostic imaging. Methods: Fe3O4, Fe3O4@TiO2, and Fe3O4@SiO2 nanoparticles were synthesized via co-precipitation at varying temperatures from iron salt precursors. Fourier transform infrared spectroscopy (FTIR) was used to confirm the presence of Fe–O bonds, while X-ray diffraction (XRD) was employed to determine the crystalline phases and estimate average crystallite sizes. Morphological analysis and particle size distribution were assessed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and transmission electron microscopy (TEM). Magnetic properties were investigated using vibrating sample magnetometry (VSM). Results: FTIR spectra exhibited characteristic Fe–O vibrations at 543 cm−1 and 555 cm−1, indicating the formation of magnetite. XRD patterns confirmed a dominant cubic magnetite phase, with the presence of rutile TiO2 and stishovite SiO2 in the coated samples. The average crystallite sizes ranged from 24 to 95 nm. SEM and TEM analyses revealed particle sizes between 5 and 150 nm with well-defined core–shell morphologies. VSM measurements showed saturation magnetization (Ms) values ranging from 40 to 70 emu/g, depending on the synthesis temperature and shell composition. The highest Ms value was obtained for uncoated Fe3O4 synthesized at 94 °C. Conclusions: The synthesized Fe3O4-based core–shell nanomaterials exhibit desirable structural, morphological, and magnetic properties for use as contrast agents. Their tunable magnetic response and nanoscale dimensions make them promising candidates for advanced diagnostic imaging applications. Full article
(This article belongs to the Section Medical Imaging and Theranostics)
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17 pages, 7311 KiB  
Article
Fabrication of Cu-Al-Mn-Ti Shape Memory Alloys via Selective Laser Melting and Its Nano-Precipitation Strengthening
by Lijun He, Yan Li, Qing Su, Xiya Zhao and Zhenyu Jiang
Micromachines 2025, 16(8), 857; https://doi.org/10.3390/mi16080857 - 25 Jul 2025
Viewed by 239
Abstract
A Cu-11.85Al-3.2Mn-0.1Ti shape memory alloy (SMA) with excellent superelasticity and shape memory effect was successfully fabricated via selective laser melting (SLM). Increasing the energy density enhanced grain refinement, achieving a 90% refinement rate compared to cast alloy, with an average width of ~0.15 [...] Read more.
A Cu-11.85Al-3.2Mn-0.1Ti shape memory alloy (SMA) with excellent superelasticity and shape memory effect was successfully fabricated via selective laser melting (SLM). Increasing the energy density enhanced grain refinement, achieving a 90% refinement rate compared to cast alloy, with an average width of ~0.15 µm. Refined martensite lowered transformation temperatures and increased thermal hysteresis. Nanoscale Cu2TiAl phases precipitated densely within the matrix, forming a dual strengthening network combining precipitation hardening and dislocation hardening. This mechanism yielded a room-temperature tensile strength of 829.07 MPa, with 6.38% fracture strain. At 200 °C, strength increased to 883.68 MPa, with 12.26% strain. The maximum tensile strength represents a nearly 30% improvement on existing laser-melted quaternary Cu-based SMAs. Full article
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15 pages, 6193 KiB  
Article
Microscopy Study of (Ti,Nb)(C,N) Precipitation in Microalloyed Steels Under Continuous Casting Conditions
by Fangyong Xu, Daoyao Liu, Wei Wang, Brian G. Thomas, Tianxu Wu, Kun Xu and Zhan Zhang
Materials 2025, 18(15), 3445; https://doi.org/10.3390/ma18153445 - 23 Jul 2025
Viewed by 247
Abstract
The continuous casting of Ti-Nb microalloyed steel was simulated with high temperature confocal laser scanning microscopy (HTCLSM). Evolution of the sample surface morphology was observed in-situ, during cooling conditions chosen to represent different locations in a cast slab. Calculations with a thermodynamics model [...] Read more.
The continuous casting of Ti-Nb microalloyed steel was simulated with high temperature confocal laser scanning microscopy (HTCLSM). Evolution of the sample surface morphology was observed in-situ, during cooling conditions chosen to represent different locations in a cast slab. Calculations with a thermodynamics model of carbonitride precipitate formation agreed with the transmission electron microscopy (TEM) analysis that fine reliefs observed on the sample surface were actually caused by interior precipitation of (Ti,Nb)(C,N). Precipitation and the resulting reliefs changed with location beneath the slab surface, simulated casting speed, and steel composition. With the same casting speed and steel composition, reliefs in the simulated slab surface sample appeared earlier and were larger than in the slab center. With increased casting speed, reliefs were observed later and decreased in size. With increased titanium or niobium content, reliefs appeared earlier and increased in number. TEM measurement showed that the precipitate diameters were mainly smaller than 4 nm, with a few between 4 and 8 nm. The property of surface reliefs observed via HTCLSM correlated qualitatively with the number and size of internal precipitates measured with TEM, showing this to be an effective tool for indirectly characterizing nanoscale secondary phase precipitation inside the sample. Full article
(This article belongs to the Section Metals and Alloys)
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20 pages, 13326 KiB  
Article
Stress–Strain and Structural Evolution on the Localized Interface of Stainless Steel Clad Plate
by Yinpeng Wang, Bo Gao, Qiqing Tian, Chunhui Jiang, Lu Zhu, Yanguang Cao, Wei Wei and Zhaodong Li
Materials 2025, 18(14), 3255; https://doi.org/10.3390/ma18143255 - 10 Jul 2025
Viewed by 329
Abstract
By applying different heat treatment processes (furnace cooling, air cooling, and water cooling), the stress–strain behavior of the localized interfacial region in weathering steel–stainless steel clad plates was investigated using nanoindentation, along with an analysis of interfacial microstructure formation and strengthening mechanisms. The [...] Read more.
By applying different heat treatment processes (furnace cooling, air cooling, and water cooling), the stress–strain behavior of the localized interfacial region in weathering steel–stainless steel clad plates was investigated using nanoindentation, along with an analysis of interfacial microstructure formation and strengthening mechanisms. The results show that samples in the as-rolled (R), furnace-cooled (FC), air-cooled (AC), and water-cooled (WC) conditions exhibit distinct interfacial morphologies and local mechanical properties. A well-defined interfacial layer forms between the base and cladding materials, where a high density of dislocations, grain boundaries, precipitates, and nanoscale oxides significantly enhances interfacial strength, resulting in a yield strength (Rp0.2) much higher than that of either adjacent metal. Across the transition from weathering steel to stainless steel, the interfacial region consists of ferrite—interfacial layer—“new austenite”—stainless steel austenite. Its formation is predominantly governed by element diffusion, which is strongly influenced by the applied heat treatment. Variations in diffusion behavior significantly affect the microstructural evolution of the dual-phase transition zone at the interface, thereby altering the local mechanical response. Full article
(This article belongs to the Section Metals and Alloys)
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14 pages, 5112 KiB  
Article
Effect of Si Doping on Microstructure and Mechanical and Electrochemical Properties of (AlCrFeNi)100-xSix (x = 2, 4, 6) Dual-Phase Eutectic High-Entropy Alloys
by Subo Yu, Kaiwen Kang, Borui Zhang, Aoxiang Li and Gong Li
Metals 2025, 15(7), 762; https://doi.org/10.3390/met15070762 - 6 Jul 2025
Viewed by 300
Abstract
The effects of silicon (Si) doping on the microstructure, mechanical properties, and electrochemical corrosion behavior of dual-phase eutectic high-entropy alloys (AlCrFeNi)100-xSix (x = 2, 4, 6 at.%) were systematically investigated. The results reveal that with increasing Si content, all three [...] Read more.
The effects of silicon (Si) doping on the microstructure, mechanical properties, and electrochemical corrosion behavior of dual-phase eutectic high-entropy alloys (AlCrFeNi)100-xSix (x = 2, 4, 6 at.%) were systematically investigated. The results reveal that with increasing Si content, all three alloys maintain a sunflower-like eutectic microstructure composed of A2 and B2 phases, characterized by an expanding central region and a densification and refinement of the lamellar two-phase structure in the petal regions; the volume of phase B2 gradually increases, accompanied by the precipitation of nanoscale B2 particles. The test results of mechanical properties show that Si doping enhances the compressive strength and Vickers hardness but significantly reduces ductility, exhibiting a typical inverse strength–ductility relationship. Electrochemical corrosion tests demonstrate that higher Si content deteriorates corrosion resistance, with corrosion predominantly occurring in the B2 phase. Among the studied alloys, the Si2 variant exhibits the most balanced overall performance. This work provides valuable insights into the role of Si in tuning the microstructure and properties of eutectic high-entropy alloys and methodology for their compositional design and engineering applications. Full article
(This article belongs to the Special Issue High-Entropy Alloys: Processing and Properties)
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18 pages, 5928 KiB  
Article
The Influence of Direct Aging on TiB2/Al–Si–Mg Composites Fabricated by LPBF: Residual Stress, Mechanical Properties and Microstructure
by Peng Rong, Xin Fang, Yirui Chang, Yong Chen, Dan Huang and Yang Li
Coatings 2025, 15(7), 780; https://doi.org/10.3390/coatings15070780 - 2 Jul 2025
Viewed by 576
Abstract
This study systematically investigates the effects of various direct aging (DA) treatments on the residual stress, mechanical properties, and microstructure of laser powder bed fusion (LPBF) fabricated TiB2/AlSi7Mg composites. The results demonstrate that during aging at 120 °C, the hardness exhibits [...] Read more.
This study systematically investigates the effects of various direct aging (DA) treatments on the residual stress, mechanical properties, and microstructure of laser powder bed fusion (LPBF) fabricated TiB2/AlSi7Mg composites. The results demonstrate that during aging at 120 °C, the hardness exhibits a typical age-hardening behavior. The residual stress relief rate increased to 45.1% after 336 h, although the stress relief rate significantly diminished over time. Increasing the aging temperature effectively enhanced residual stress removal efficiency, with reductions of approximately 40% and 62% observed after aging at 150 °C for 4 h and 190 °C for 8 h, respectively. Regarding mechanical properties, aging at 150 °C for 4 h resulted in an optimal synergy in yield strength (YS = 358 MPa) and elongation (EL = 9.2%), followed by aging at 190 °C for 8 h with YS of 320 MPa and EL of 7.0%. Microstructural analysis revealed that low temperature aging promotes the formation of nanoscale Si precipitates, which enhance strength through the Orowan mechanism. In contrast, high temperature annealing disrupts the metastable cellular structure, leading to the loss of strengthening effects. This work provides fundamental insights for effective residual stress management and performance optimization of LPBF Al–Si–Mg alloys. Full article
(This article belongs to the Special Issue Advanced Surface Technology and Application)
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18 pages, 9256 KiB  
Article
Effect of Rare Earth Element Ce on Nanoscale (Ti, Nb) C Precipitates and Mechanical Properties of High-Strength Low-Alloy Weathering Steel
by Yunlong Wang, Rui Zhu, Hairui Ma, Guohua Ding, Limeng Liang, Weiwei Sun and Yongxia Wang
Materials 2025, 18(13), 3033; https://doi.org/10.3390/ma18133033 - 26 Jun 2025
Viewed by 306
Abstract
This study investigates the influence of rare earth element Ce addition on the nanoscale precipitation, microstructure, and mechanical properties of Ti-containing secondary phases in high-strength low-alloy weathering steel. Mechanical property testing and microstructural characterization were performed on experimental samples subjected to rolling-aging treatment. [...] Read more.
This study investigates the influence of rare earth element Ce addition on the nanoscale precipitation, microstructure, and mechanical properties of Ti-containing secondary phases in high-strength low-alloy weathering steel. Mechanical property testing and microstructural characterization were performed on experimental samples subjected to rolling-aging treatment. The results demonstrate that the addition of Ce promotes coarsening of nanoscale precipitates, thereby diminishing their precipitation strengthening effect. At a 0.11% Ce content, an increase in inclusions was observed, leading to crack formation during hot deformation. However, Ce addition also refines inclusion size and modifies inclusion types, contributing to steel purification. Through austenite recrystallization zone rolling combined with an isothermal process, a high-strength ferritic weathering steel with nanoscale precipitates was fabricated, exhibiting a yield strength of 635 MPa, tensile strength of 750 MPa, and elongation of 21.2%. Precipitation strengthening plays a critical role in enhancing the room-temperature strength of ferritic steel. Full article
(This article belongs to the Section Metals and Alloys)
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11 pages, 2528 KiB  
Article
Synergistic Effects of Co on Nanoscale Dual-Precipitation in 2.3 GPa-Grade Steel
by Aijun Li, Jiaxin Liu, Yangxin Wang and Chundong Hu
Materials 2025, 18(13), 2979; https://doi.org/10.3390/ma18132979 - 23 Jun 2025
Viewed by 314
Abstract
A novel ultrahigh-strength steel with Co and strengthened through nanoscale precipitation was developed. We found that the Co element had a synergistic effect on the precipitation process. The simulation results indicate that adding Co to steel can suppress the tracer diffusion coefficients of [...] Read more.
A novel ultrahigh-strength steel with Co and strengthened through nanoscale precipitation was developed. We found that the Co element had a synergistic effect on the precipitation process. The simulation results indicate that adding Co to steel can suppress the tracer diffusion coefficients of all the elements in the steel, hindering the atomic self-diffusion rate and long-range diffusion effect. A decrease in the atomic diffusion rate of precipitations will affect the nucleation, distribution, and growth of precipitations. The Atom probe tomography (APT) results indicate that the Co element not only dispersed uniformly in the matrix itself but also induced the uniform distribution of the precipitation phases. During the nucleation process of the precipitation, the rejected Co atoms formed small regions of high Co concentrations around the precipitation, inhibiting the coarsening of the precipitation. Under the synergistic effect of Co, the high number density of nanoscale NiAl and M2C enhanced the strength of the steel. Full article
(This article belongs to the Section Metals and Alloys)
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12 pages, 3510 KiB  
Article
Anomalous Precipitation of the γ-Fe Phase in Fe-Based Nanocrystalline Alloys and Its Impact on Soft Magnetic Properties
by You Wu, Lingxiang Shi, Ranbin Wang, Jili Jia, Wenhui Guo, Yunshuai Su, Hengtong Bu, Siqi Xiang, Weihong Yang, Mingli Fu, Yang Shao and Kefu Yao
Materials 2025, 18(12), 2867; https://doi.org/10.3390/ma18122867 - 17 Jun 2025
Viewed by 424
Abstract
High-Cu-content (Cu-content > 1.3 at.%) nanocrystalline alloys exhibit wide heat-treatment windows and favorable soft magnetic properties due to the presence of pre-existing α-Fe nanocrystals. By fabricating ribbons with varying thicknesses to tailor cooling rates, distinct structural characteristics were achieved in Fe82B [...] Read more.
High-Cu-content (Cu-content > 1.3 at.%) nanocrystalline alloys exhibit wide heat-treatment windows and favorable soft magnetic properties due to the presence of pre-existing α-Fe nanocrystals. By fabricating ribbons with varying thicknesses to tailor cooling rates, distinct structural characteristics were achieved in Fe82B16.5Cu1.5 alloy ribbons. Notably, the face-centered cubic (fcc) γ-Fe phase was identified in Fe-based nanocrystalline alloys. The precipitation of the fcc γ-Fe phase originates from a phase-selection mechanism under specific cooling conditions, while its retention in the as-quenched ribbon with a thickness of 27 μm is attributed to kinetic suppression during rapid cooling and the nanoscale stabilization effect. The formation of the fcc γ-Fe phase significantly reduced the saturation flux density (Bs) and increased coercivity (Hc), concurrently destabilizing the residual amorphous matrix. By suppressing the precipitation of the γ-Fe and Fe3B phases through precise control of ribbon thickness and annealing parameters, the alloy ribbon with a thickness of 16 μm achieved an optimal combination of Bs (1.82 T) and Hc (8.3 A/m). These findings on anomalous fcc γ-Fe phase precipitation provide novel insights into metastable phase engineering and offer structural design guidelines for alloys containing pre-existing α-Fe nanocrystals. Full article
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15 pages, 5972 KiB  
Article
Developing NiAl-Strengthened ULCB Steels by Controlling Nanoscale Precipitation and Reversed Austenite
by Jize Guo, Xiyang Chai, Shuo Gong, Zemin Wang and Tao Pan
Materials 2025, 18(12), 2822; https://doi.org/10.3390/ma18122822 - 16 Jun 2025
Viewed by 322
Abstract
In this study, a strategy was adopted to promote the formation of NiAl precipitates with the aim of enhancing strength by incorporating a 0.2 wt.% Al into a traditional ultra-low carbon bainitic (ULCB) steel alloy. By integrating thermo-mechanical control processing (TMCP) and a [...] Read more.
In this study, a strategy was adopted to promote the formation of NiAl precipitates with the aim of enhancing strength by incorporating a 0.2 wt.% Al into a traditional ultra-low carbon bainitic (ULCB) steel alloy. By integrating thermo-mechanical control processing (TMCP) and a tailored tempering process, a new-generation steel with an outstanding combination of properties has been successfully developed for shipbuilding and marine engineering equipment. It features a yield strength of 880 MPa, a yield ratio of 0.84, and an impact toughness of 175 J. The precipitation characteristics of nanoscale particles in this steel, including NiAl intermetallics and carbides, were systematically investigated. The results show that the alloy with low Al addition formed NiAl precipitates during tempering. The high-density distributions of NiAl, (Mo, V)C, and (Ti, V, Nb)C precipitates, which exhibit slow coarsening kinetics, played a dominant role in enhancing the strength of the tempered steel. In addition to precipitation, the microstructure before and after tempering was also analyzed. It was observed that a granular bainite morphology was favorable for decreasing the yield ratio. Additionally, the formation of reverse-transformed austenite during tempering was critical for retaining toughness despite substantial strength gains. Finally, theoretical modeling was employed to quantitatively assess the contributions of these microstructural modifications to yield strength enhancement of thermo-mechanical controlled processing (TMCP) and tempered steel. This study establishes a fundamental basis for subsequent industrial-scale development and practical engineering applications of novel products. Full article
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14 pages, 13464 KiB  
Article
The Design and Microstructure Evolution Mechanism of New Cr1.3Ni2TiAl, CoCr1.5NiTi1.5Al0.2, and V0.3CoCr1.2NiTi1.1Al0.2 Eutectic High-Entropy Alloys
by Xin Zhang, Haitao Yan, Yao Xiao, Wenxin Feng and Yangchuan Cai
Metals 2025, 15(6), 613; https://doi.org/10.3390/met15060613 - 29 May 2025
Viewed by 338
Abstract
To expand the fundamental understanding of eutectic high-entropy alloys (EHEAs), three novel alloy systems—Cr1.3Ni2TiAl, CoCr1.5NiTi1.5Al0.2, and V0.3CoCr1.2NiTi1.1Al0.2—were rationally designed through synergistic phase diagram analysis and [...] Read more.
To expand the fundamental understanding of eutectic high-entropy alloys (EHEAs), three novel alloy systems—Cr1.3Ni2TiAl, CoCr1.5NiTi1.5Al0.2, and V0.3CoCr1.2NiTi1.1Al0.2—were rationally designed through synergistic phase diagram analysis and thermodynamic parameter calculations. Comprehensive microstructural characterization coupled with mechanical property evaluation revealed that these alloys possess FCC+BCC dual-phase architectures with atypical irregular eutectic morphologies. Notably, progressive microstructural evolution was observed, including amplified grain boundary density and the emergence of brittle nanoscale precipitates. Mechanical testing demonstrated superior compressive yield strengths in these alloys compared to conventional FCC+BCC EHEAs with ordered eutectic structures, albeit accompanied by reduced fracture strain. The Cr1.3Ni2TiAl alloy exhibited optimal ductility, with a maximum fracture strain of 15.6%, while V0.3CoCr1.2NiTi1.1Al0.2 achieved peak strength, with a compressive yield strength of 1389.5 MPa. Multiscale analysis suggests that the enhanced mechanical performance arises from the synergistic interplay between irregular eutectic configurations, expanded grain boundary area, and precipitation strengthening mechanisms. Full article
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16 pages, 3686 KiB  
Article
Hydrogels Powered by Nanoemulsion Technology for the Topical Delivery of Acmella oleracea Extract
by Eleonora Spinozzi, Marco Cespi, Marta Ferrati, Riccardo Petrelli, Filippo Maggi, Junbiao Wang, Sunday Segun Alimi, Diego Romano Perinelli and Giulia Bonacucina
Pharmaceutics 2025, 17(5), 625; https://doi.org/10.3390/pharmaceutics17050625 - 8 May 2025
Viewed by 602
Abstract
Background/Objectives: Natural products are gaining increasing importance due to the large variety of biological activities exerted by their constituents. Among these, the products deriving from Acmella oleracea (L.) R.K. Jansen can be exploited for their local anaesthetic, myorelaxant, anti-inflammatory/analgesic, and antifungal properties. [...] Read more.
Background/Objectives: Natural products are gaining increasing importance due to the large variety of biological activities exerted by their constituents. Among these, the products deriving from Acmella oleracea (L.) R.K. Jansen can be exploited for their local anaesthetic, myorelaxant, anti-inflammatory/analgesic, and antifungal properties. In this regard, there is a need to develop novel formulations for the topical delivery of A. oleracea-derived extracts to widen their use in the pharmaceutical and cosmetic fields. Methods: Nanoformulations, i.e., nanoemulsions (NEs) and microemulsions (MEs), were investigated as a strategy to encapsulate an extract from A. oleracea at the nanoscale level in water and then incorporated into xanthan gum-based hydrogels. Results: Only NEs provided a physically stable formulation, while the precipitation of solid hydrophobic components from the extract was observed during ME preparation under all tested conditions despite the use of ethyl oleate as an oily co-solvent. The optimized NE-based hydrogel remained physically stable over six months, as confirmed by rheological measurements and polarized optical microscope observation, without a phase separation phenomenon. Therefore, NEs resulted more suitable nanodispersed systems than MEs for the encapsulation of A. oleracea extract, which contains a large amount of hydrophobic constituents that are solid at room temperature. Furthermore, the sustained spilanthol release across an artificial membrane (Franz cell apparatus) and the cytotoxic profile on HaCaT cell line support its potential topical application. Conclusions: The outcomes of this study provided valuable insights into the formulation of A. oleracea extract, broadening its fields of applicability, including topical administration. Full article
(This article belongs to the Section Drug Delivery and Controlled Release)
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18 pages, 8764 KiB  
Article
Synergistic Removal of Cr(VI) Utilizing Oxalated-Modified Zero-Valent Iron: Enhanced Electron Selectivity and Dynamic Fe(II) Regeneration
by Song Hou, Jiangkun Du, Haibo Ling, Sen Quan, Jianguo Bao and Chuan Yi
Nanomaterials 2025, 15(9), 669; https://doi.org/10.3390/nano15090669 - 28 Apr 2025
Viewed by 476
Abstract
To address the challenges of environmental adaptability and passivation in nanoscale zero-valent iron (nFe0) systems, we developed oxalate-modified nFe0 (nFeoxa) through a coordination-driven synthesis strategy, aiming to achieve high-efficiency Cr(VI) removal with improved stability and reusability. Structural characterization [...] Read more.
To address the challenges of environmental adaptability and passivation in nanoscale zero-valent iron (nFe0) systems, we developed oxalate-modified nFe0 (nFeoxa) through a coordination-driven synthesis strategy, aiming to achieve high-efficiency Cr(VI) removal with improved stability and reusability. Structural characterization (STEM and FT-IR) confirmed the formation of a FeC2O4/nFe0 heterostructure, where oxalate coordinated with Fe(II) to construct a semiconductor interface that effectively inhibits anoxic passivation while enabling continuous electron supply, achieving 100% Cr(VI) removal efficiency within 20 min at an optimal oxalate/Fe molar ratio of 1/29. Mechanistic studies revealed that the oxalate ligand accelerates electron transfer from the Fe0 core to the surface via the FeC2O4-mediated pathway, as evidenced by EIS and LSV test analyses. This process dynamically regenerates surface Fe(II) active sites rather than relying on static-free Fe(II) adsorption. XPS and STEM further demonstrated that Cr(VI) was reduced to Cr(III) and uniformly co-precipitated with Fe(II/III)-oxalate complexes, effectively immobilizing chromium. The synergy between the protective semiconductor layer and the ligand-enhanced electron transfer endows nFeoxa with superior reactivity. This work provides a ligand-engineering strategy to design robust nFe0-based materials for sustainable remediation of metal oxyanion-contaminated water. Full article
(This article belongs to the Section Environmental Nanoscience and Nanotechnology)
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15 pages, 20924 KiB  
Article
The Effect of Nb Addition on the Microstructural Evolution and Mechanical Properties of 50W–Ni–Fe Alloy
by Tianhao Wu, Wensheng Liu, Yunzhu Ma, Youteng Duan, Yifan Han, Ziqi Meng and Qingshan Cai
Crystals 2025, 15(5), 411; https://doi.org/10.3390/cryst15050411 - 28 Apr 2025
Viewed by 489
Abstract
Optimizing the design of low-tungsten-content alloys represents an effective approach to address the insufficient strength and toughness of conventional tungsten alloys. This study focuses on the design and fabrication of low-tungsten-content alloys, specifically investigating the effects of Nb addition on the low-temperature sintering [...] Read more.
Optimizing the design of low-tungsten-content alloys represents an effective approach to address the insufficient strength and toughness of conventional tungsten alloys. This study focuses on the design and fabrication of low-tungsten-content alloys, specifically investigating the effects of Nb addition on the low-temperature sintering microstructure and mechanical properties of 50W–Ni–Fe alloy. The results demonstrate that Nb significantly lowers the liquid phase formation temperature, shifting the densification mechanism from solid phase sintering to liquid phase sintering. Nb primarily dissolves in the γ-(Ni,Fe) matrix phase and forms nanoscale γ″-Ni3Nb precipitates. These γ″-Ni3Nb precipitates maintain coherent interfaces with the γ-(Ni,Fe) matrix phase, exhibiting excellent interfacial bonding, which markedly enhances the hardness and modulus of the matrix phase. Through the strengthening effects of solid solution strengthening and precipitation strengthening, the tensile strength of the alloy increases to 1259 MPa while maintaining a total elongation of 23.1%. The fracture mode of the 50W-Ni-Fe-Nb alloy transitions to a mixed mechanism involving cleavage fracture of W and ductile rupture of the matrix phase. Full article
(This article belongs to the Special Issue Design, Microstructure and Mechanical Properties of Cu-Based Alloys)
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