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20 pages, 2371 KB  
Article
Does Grazing or Climate Change Transform Vegetation More Rapidly? A Case Study of Calcareous Sandy Grasslands in the Pannonian Region
by Ildikó Turcsányi-Járdi, Eszter Saláta-Falusi, Szilárd Szentes, Zoltán Kende, László Sipos, Gergő Péter Kovács, Tünde Szabó-Szöllösi, Gabriella Fintha, Leonárd Sári, Péter Penksza, Zsombor Wagenhoffer and Károly Penksza
Land 2026, 15(1), 72; https://doi.org/10.3390/land15010072 - 31 Dec 2025
Viewed by 238
Abstract
In this study, we compare two contrasting years within the 2020–2025 period—one characterized by extreme heat and drought, and another by unusually high precipitation. We used five years of climatic data provided by the Hungarian Meteorological Service (OMSZ), along with vegetation activity indices [...] Read more.
In this study, we compare two contrasting years within the 2020–2025 period—one characterized by extreme heat and drought, and another by unusually high precipitation. We used five years of climatic data provided by the Hungarian Meteorological Service (OMSZ), along with vegetation activity indices (NDVI—Normalized Difference Vegetation Index; NDWI—Normalized Difference Water Index) derived from Sentinel-2A satellite imagery. In parallel, during three years of the study period (2020, 2022, and 2025), we collected five phytosociological relevés in each of the five vegetation types subjected to different management regimes. For data analysis, we applied Principal Component Analysis (PCA), Detrended Correspondence Analysis (DCA), and the Additive Main Effects and Multiplicative Interaction (AMMI) model. Vegetation index patterns were compared with the relative water requirements of the constituent plant species. In the ungrazed dry sandy site, climatic fluctuations did not significantly affect vegetation composition and the habitat remained a stable open sandy grassland. Among the four grazed sites, grazing intensity remained unchanged during the study in three cases (N1, N2, and SZ). Thus, vegetation changes observed in these areas can be attributed to climatic factors. Vegetation composition shifted in N1 and N2, whereas no significant change was detected in the drier SZ site. This indicates higher resistance to grazing in SZ, which can therefore be sustainably used as pasture, while the N1–N2 sites responded sensitively to precipitation variability under identical grazing pressure and are better suited for use as meadows. The most pronounced changes occurred at the P site, which had previously functioned as an animal resting area and began regenerating after abandonment in 2022. Vegetation composition shifted markedly within two years, demonstrating that land-use practices exert a stronger influence on sandy grassland vegetation than climatic fluctuations. Overall, the drier habitats were more resilient to both grazing pressure and climatic variability and are suitable for grazing, whereas the moister vegetation types were more sensitive and should preferably be managed as hay meadows. Full article
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22 pages, 10256 KB  
Article
Comparative Study on the Wear Resistance of C&B-Type Polymer Materials for Temporary Crowns Manufactured Using 3D DLP Printing Technology
by Marcel Firlej, Daniel Pieniak, Andrzej Snarski-Adamski, Barbara Biedziak, Agata Niewczas, Jana Petru, Jonas Matijošius, Zbigniew Krzysiak and Katarzyna Zaborowicz
Materials 2025, 18(24), 5478; https://doi.org/10.3390/ma18245478 - 5 Dec 2025
Viewed by 444
Abstract
DLP (Digital Light Processing) 3D printing enables precise fabrication of temporary crowns. Tribological properties of these materials affect clinical durability, wear resistance, and masticatory function. This study compared three C&B-type photopolymers for DLP-printed temporary crowns: Gr-17.1 temporary It, Gr-17 temporary (Pro3dure), and VarseoSmile [...] Read more.
DLP (Digital Light Processing) 3D printing enables precise fabrication of temporary crowns. Tribological properties of these materials affect clinical durability, wear resistance, and masticatory function. This study compared three C&B-type photopolymers for DLP-printed temporary crowns: Gr-17.1 temporary It, Gr-17 temporary (Pro3dure), and VarseoSmile Temp (BEGO). Samples were printed, post-processed, and polished. Surface topography (Sa, Sz) was measured via white light interferometry, and scratch resistance was evaluated with a Rockwell indenter. Sliding wear tests under wet conditions (37 °C, 90% RH) were conducted using an SRV 4 tester at 25 N for 20,000 cycles. VarseoSmile Temp showed the highest scratch and sliding wear resistance, with the lowest mean volumetric wear (0.025 mm3) and residual scratch depth, reflecting its higher inorganic filler content (30–50 wt%). Gr-17.1 had the most stable coefficient of friction (~0.3), while Gr-17 experienced the greatest wear (0.235 mm3). No direct correlation between friction and wear was observed. These findings indicate that wear resistance depends on microstructure and filler content, supporting tribological testing as a tool to evaluate the durability of 3D-printed temporary crowns. Full article
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13 pages, 5096 KB  
Article
Microstructure and Mechanical Properties of Friction Stir Welded the Novel Al-Mg-Zn-Si Alloy
by Junzhe Huang, Ying Li, Xiwu Li, Hongwei Yan, Lizhen Yan, Kai Wen, Yanan Li, Guanjun Gao, Kai Zhu, Mingyang Yu, Yongan Zhang and Baiqing Xiong
Materials 2025, 18(23), 5269; https://doi.org/10.3390/ma18235269 - 21 Nov 2025
Viewed by 659
Abstract
The high-Mg-content Al-Mg-Zn-Si alloy, as a novel aluminum alloy, exhibits excellent strength, toughness, and corrosion resistance, demonstrating significant application potential in lightweight structural components for aerospace, weapon systems, rail transportation, and other fields. In this study, friction stir welding was employed to weld [...] Read more.
The high-Mg-content Al-Mg-Zn-Si alloy, as a novel aluminum alloy, exhibits excellent strength, toughness, and corrosion resistance, demonstrating significant application potential in lightweight structural components for aerospace, weapon systems, rail transportation, and other fields. In this study, friction stir welding was employed to weld the high-Mg-content Al-Mg-Zn-Si alloy. Subsequent aging treatment was applied to establish the relationship between the mechanical properties and microstructural characteristics of the welded joint, aiming to elucidate the strengthening mechanisms of the new alloy and provide insights for achieving high-quality welds. The results indicate that the microhardness profile of the as-welded joint exhibited a “W” shape, with overall low hardness values and minor differences between zones. After the aging treatment, the microhardness increased significantly in the base material (BM), the thermo-mechanically affected zone (TMAZ), and the stir zone (SZ), whereas the heat-affected zone (HAZ) adjacent to the SZ exhibited only a marginal increase, making it the softest region in the aged joint. The yield strength and ultimate tensile strength of the aged joint increased to 327 MPa and 471 MPa, respectively. The enhancement in microhardness and strength after aging treatment was attributed to the precipitation of numerous nano-sized T-phase particles within grains. Interestingly, the tensile samples of the aged joint fractured in the high-hardness SZ instead of the low-hardness HAZ. This fracture behavior was primarily attributed to continuous grain boundary precipitates, which reduced intergranular cohesion. In contrast, the elongated grain structure in the HAZ more effectively resisted intergranular crack propagation compared to the equiaxed grains in the SZ. Full article
(This article belongs to the Section Metals and Alloys)
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12 pages, 709 KB  
Article
Effects of Personality Styles on Clinical Response to Intermittent Theta Burst Stimulation for Depression
by Mohamed A. Abdelnaim, Tobias Hebel, Katharina Kerkel, Berthold Langguth, Martin Schecklmann, Susanne Staudinger and Andreas Reissmann
J. Clin. Med. 2025, 14(21), 7612; https://doi.org/10.3390/jcm14217612 - 27 Oct 2025
Viewed by 651
Abstract
Introduction: Major depressive disorder (MDD) is a common and often treatment-resistant condition, with many patients showing only partial or minimal response to standard therapies. Repetitive transcranial magnetic stimulation (rTMS) is a well-established, non-invasive treatment for depression, though individual response varies considerably. While demographic [...] Read more.
Introduction: Major depressive disorder (MDD) is a common and often treatment-resistant condition, with many patients showing only partial or minimal response to standard therapies. Repetitive transcranial magnetic stimulation (rTMS) is a well-established, non-invasive treatment for depression, though individual response varies considerably. While demographic and clinical predictors have been explored, the impact of personality styles on rTMS outcomes remains underinvestigated. Herein, we aimed to explore whether personality styles influence treatment response to rTMS. Methods: This retrospective study included 63 in- and outpatients with depressive episodes treated with intermittent theta-burst stimulation (iTBS) between September 2020 and December 2022. Patients were assessed before and after treatment using the 21-item Hamilton Depression Rating Scale (HAMD-21) and the self-reported Major Depression Inventory (MDI). Personality styles were evaluated using the German Persönlichkeits-Stil-und-Störungs-Inventar (PSSI), a dimensional measure of 14 personality styles. Statistical analyses included paired-samples t-tests to assess symptom change and linear regression models to examine whether personality styles predicted treatment outcomes. Effect sizes were reported as Cohen’s d. Results: Patients showed a significant reduction in depressive symptoms following iTBS (HAMD-21: t(62) = 10.86, p < 0.001, d = 1.37. MDI: t(62) = 8.55, p < 0.001, d = 1.06). Stepwise regression for the MDI identified critical–negativistic (NT) and reserved–schizoid (SZ) styles as significant predictors, explaining approximately 16% of the variance (R2 = 0.159, p = 0.007). When entered simultaneously in a regression model for the HAMD-21, these same traits also predicted symptom change, though the effect was smaller (R2 = 0.108, p = 0.033). Higher scores of critical–negativistic (NT) style were associated with better improvement, whereas higher scores of reserved–schizoid (SZ) style were associated with less improvement. Conclusions: This study confirms the overall efficacy of rTMS in reducing depressive symptoms. While SZ and NT traits showed some predictive value for treatment response—particularly on self-reported outcomes—their influence was modest and inconsistent. Based on our findings, there is no reason why patients with depression and specific personality styles, or even comorbid personality disorders, should be denied rTMS treatment. Full article
(This article belongs to the Section Mental Health)
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16 pages, 2918 KB  
Article
Surface Engineering of Natural Killer Cells with Lipid-Based Antibody Capture Platform for Targeted Chemoimmunotherapy
by Su Yeon Lim, Yeongbeom Kim, Hongbin Kim, Seungmin Han, Jina Yun, Hyun-Ouk Kim, Suk-Jin Ha, Sehyun Chae, Young-Wook Won and Kwang Suk Lim
Pharmaceutics 2025, 17(10), 1285; https://doi.org/10.3390/pharmaceutics17101285 - 1 Oct 2025
Viewed by 1090
Abstract
Next-generation cancer immunotherapy increasingly combines tumor-targeting antibodies or antibody–drug conjugates (ADCs) with immune effector cells to enhance therapeutic precision. However, many existing approaches rely on genetic modification or complex manufacturing, limiting their clinical scalability and rapid deployment. To address this issue, we developed [...] Read more.
Next-generation cancer immunotherapy increasingly combines tumor-targeting antibodies or antibody–drug conjugates (ADCs) with immune effector cells to enhance therapeutic precision. However, many existing approaches rely on genetic modification or complex manufacturing, limiting their clinical scalability and rapid deployment. To address this issue, we developed an antibody capture protein (ACP)-based surface engineering platform that enables the rapid, reversible, and non-genetic functionalization of NK cells with therapeutic antibodies or ADCs. This approach uses a DMPE-PEG-lipid conjugate to anchor thiolated protein A (ACP) to the NK cell membrane via hydrophobic insertion, thereby stably and selectively binding to the Fc region of IgG molecules. Using this strategy, we developed ACP-modified NK cells (AC-NKs) that can selectively capture therapeutic antibodies (trastuzumab (TZ), trastuzumab-emtansine (T-DM1), and sacituzumab (SZ)) pre-bound to each target antigen on tumor cells and induce antigen-specific cytotoxic responses. The resulting AC-NKs exhibited enhanced tumor recognition and cytotoxicity against HER2-positive and Trop-2-positive cancer cells in vitro. Compared with conventional combination therapies, AC-NKs enhanced immune activation, as demonstrated by effective delivery of cytotoxic agents, enhanced cancer cell engagement, and upregulation of CD107a expression. Notably, the system supports multiple antigen targeting and tunable antibody loading, enabling adaptation to tumor heterogeneity and resistant phenotypes. This platform might also provide a simple, scalable, and safe method for rapidly developing programmable immune cell therapies without genetic modification. Its versatility supports multi-antigen targeting and broad applicability across NK and T cell therapies, offering a promising path toward personalized, off-the-shelf chemoimmunotherapy. Full article
(This article belongs to the Special Issue Advanced Drug Delivery Systems for Targeted Immunotherapy)
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27 pages, 8651 KB  
Article
Effect of Back-Tempering on the Wear and Corrosion Properties of Multiple-Pass Friction Stir Processed High-Speed Steel
by Quan Liu, Shiye Li, Guochong Rao, Xiaomi Chen, Kun Liu, Min Zhou, Dawei Guo, Valentino A. M. Cristino, Kin-Ho Lo, Lap-Mou Tam and Chi-Tat Kwok
Materials 2025, 18(17), 4125; https://doi.org/10.3390/ma18174125 - 2 Sep 2025
Viewed by 1101
Abstract
In this study, a scalable surface modification strategy for M2 high-speed steel was applied using multiple-pass friction stir processing (FSP) with overlapping ratios of 25%, 50%, and 75%. A comprehensive investigation of the microstructure, surface hardness, wear, and corrosion resistance was conducted to [...] Read more.
In this study, a scalable surface modification strategy for M2 high-speed steel was applied using multiple-pass friction stir processing (FSP) with overlapping ratios of 25%, 50%, and 75%. A comprehensive investigation of the microstructure, surface hardness, wear, and corrosion resistance was conducted to elucidate the properties of FSPed M2 as a function of the overlapping ratio. In the single-pass FSPed M2, the major phase was martensite and the minor phases included retained austenite where refined carbides (M6C, M23C6, and MC) were detected. However, back-tempering occurred near the overlapped zone (OZ) between consecutive tracks for the multiple-pass FSPed M2. The martensite formed in the first pass was turned into tempered martensite by the thermal cycle from the subsequent pass. This back-tempering resulted in a localized decline in hardness from 900 to 650 HV0.2. Further wear tests revealed that the wear rates of the tempered zone (TZ) of the multiple-pass FSPed M2 (FSP25%: 1.40 × 10−5 mm3/N·m, FSP50%: 1.20 × 10−5 mm3/N·m and FSP75%: 1.00 × 10−5 mm3/N·m) are all higher than that of SZ of the single-pass FSPed M2 (0.75 × 10−5 mm3/N·m), indicating lower wear resistance of the TZ. Moreover, increased carbide content in the TZ led to the depletion of passivating elements near proximity of the tempered martensite, acting as the active sites for selective corrosion attack. The corrosion potential (Ecorr) and corrosion current density (Icorr) increased significantly, with values of −397.6 ± 5.6 mV and 9.5 ± 0.8 μA·cm−2 for FSP25%, −424.4 ± 6.0 mV and 14.7 ± 1.7 μA·cm−2 for FSP50%, and −440.9 ± 2.8 mV and 17.1 ± 1.9 μA·cm−2 for FSP75%. Full article
(This article belongs to the Special Issue Study on Electrochemical Behavior and Corrosion of Materials)
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16 pages, 2126 KB  
Article
Characteristic Influence of Cerium Ratio on PrMn Perovskite-Based Cathodes for Solid Oxide Fuel Cells
by Esra Balkanlı Ünlü, Meltem Karaismailoğlu Elibol and Halit Eren Figen
Catalysts 2025, 15(8), 786; https://doi.org/10.3390/catal15080786 - 18 Aug 2025
Viewed by 1048
Abstract
In this study, cerium with different ratios (x = 0 (zero), 0.1, 0.15, 0.5) was added to the PrMn structure as an A-site material to evaluate characteristic behavior as a potential cathode material for solid oxide fuel cells. The PrxCe1−x [...] Read more.
In this study, cerium with different ratios (x = 0 (zero), 0.1, 0.15, 0.5) was added to the PrMn structure as an A-site material to evaluate characteristic behavior as a potential cathode material for solid oxide fuel cells. The PrxCe1−xMnO3−δ electrocatalysts were synthesized using the sol–gel combustion method and were assessed for their electrochemical, phase, and structural properties, as well as desorption and reducibility capabilities. Phase changes, from orthorhombic to cubic structures observed upon cerium additions, were evaluated via the X-Ray diffraction method. X-Ray photoelectron spectroscopy (XPS) showed the valence states of the surface between the Ce4+/Ce3+ and Pr4+/Pr3+ redox pairs, while oxygen temperature programmed desorption (O2-TPD) analysis was used to evaluate the oxygen adsorption and desorption behavior of the electrocatalysts. Redox characterization, evaluated via hydrogen atmosphere temperature-programmed reduction (H2-TPR), revealed that a higher cerium ratio in the structure lowered the reduction temperature, suggesting a better dynamic oxygen exchange capability at a lower temperature for the Pr0.5Ce0.5MnO3−δ catalyst compared to the electrochemical behavior analysis by the electrochemical impedance spectroscopy method. Moreover, the symmetrical cell tests with Pr0.5Ce0.5MnO3−δ electrodes showed that, when combined with scandia-stabilized zirconia (ScSZ) electrolyte, the overall polarization resistance was reduced by approximately 28% at 800 °C compared to cells with yttria-stabilized zirconia (YSZ) electrolyte. Full article
(This article belongs to the Section Electrocatalysis)
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17 pages, 5119 KB  
Article
Anode-Supported SOFCs with a Bi2O3-Doped NiO–ScSZ Anode and ScSZ Electrolyte: Low-Temperature Co-Sintering and High Performance
by Shang Peng, Zhao Liu, Pairuzha Xiaokaiti, Tiancheng Fang, Jiwei Wang, Guoqing Guan and Abuliti Abudula
ChemEngineering 2025, 9(4), 66; https://doi.org/10.3390/chemengineering9040066 - 24 Jun 2025
Viewed by 1188
Abstract
In this study, a novel anode-supported solid oxide fuel cell (SOFC) comprising a Bi2O3-doped NiO-ScSZ anode and an ScSZ electrolyte was successfully fabricated via a low-temperature co-sintering process at 1300 °C. The incorporation of 3 wt% Bi2O [...] Read more.
In this study, a novel anode-supported solid oxide fuel cell (SOFC) comprising a Bi2O3-doped NiO-ScSZ anode and an ScSZ electrolyte was successfully fabricated via a low-temperature co-sintering process at 1300 °C. The incorporation of 3 wt% Bi2O3 effectively promoted the sintering of both the anode support and electrolyte layer, resulting in a dense, gas-tight electrolyte and a mechanically robust porous anode support. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the formation of phase-pure, highly crystalline ScSZ with an optimized microstructure. Electrochemical performance measurements demonstrated that the fabricated cells achieved excellent power density, reaching a peak value of 0.861 W cm−2 at 800 °C under humidified hydrogen fuel conditions. The cells maintained stable performance under dry methane operation, with a maximum power density of 0.624 W cm−2 at 800 °C, indicating resistance to carbon deposition. Gas chromatographic analyses further revealed that the Bi2O3-doped NiO-ScSZ anode facilitated earlier and more stable electrochemical oxidation of methane-derived species compared with the conventional NiO-YSZ system, even under conditions of an elevated methane partial pressure. These findings demonstrate that Bi2O3 co-doping, combined with low-temperature co-sintering, provides an effective approach for fabricating high-performance intermediate-temperature SOFCs with enhanced structural integrity and electrochemical stability. The developed methodology presents a promising pathway toward achieving cost-effective and durable SOFC technologies. Full article
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19 pages, 8554 KB  
Review
Effect of Supplementation with Probiotics in Patients with Schizophrenia: Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials
by Lu Li, Fengqi Du, Xilong Liu, Mengyao Song, Giuseppe Grosso, Maurizio Battino, Christine Boesch, He Li and Xinqi Liu
Foods 2025, 14(10), 1773; https://doi.org/10.3390/foods14101773 - 16 May 2025
Cited by 2 | Viewed by 3142
Abstract
Supplementation with probiotics seems to confer protective effects in individuals with schizophrenia (SZ), although available results are inconclusive. The aim of this study was to systematically review existing randomized clinical trials (RCTs) to critically assess the effect of probiotics on psychiatric symptoms, anthropometric [...] Read more.
Supplementation with probiotics seems to confer protective effects in individuals with schizophrenia (SZ), although available results are inconclusive. The aim of this study was to systematically review existing randomized clinical trials (RCTs) to critically assess the effect of probiotics on psychiatric symptoms, anthropometric indicators, lipid profiles, glycemic indices, inflammation, and oxidative stress in adults with SZ. A systematic search was conducted in four databases from inception until January 2025. Six RCTs were included in the quantitative analysis that demonstrated beneficial effects of probiotics on SZ severity determined via the Positive and Negative Syndrome Scale (PANSS), with significant reductions in PANSS (MD = −0.50, p = 0.001), PANSS Negative (MD = −0.31, p = 0.050), and PANSS General scores (MD = −0.33, p = 0.036), alongside reductions in body weight (MD = −0.92, p = 0.000), body mass index (MD = −0.53, p = 0.016), and total cholesterol (SMD = −0.34, p = 0.005). Furthermore, probiotic interventions reduced baseline glucose (SMD = −0.59, p = 0.000), insulin (MD = −0.68, p = 0.000), and measures of insulin sensitivity/resistance and significantly improved biomarkers of inflammation and oxidative stress. To summarize, this meta-analysis suggests that probiotics may confer beneficial effects in patients with SZ through improving psychiatric symptoms as well as markers of body weight, lipid and glucose metabolism, inflammation, and oxidative stress. Full article
(This article belongs to the Section Food Nutrition)
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15 pages, 1574 KB  
Article
The Effect of Manufacturing Factors on the Material Properties and Adhesion of C. albicans and S. mutans on Additive Denture Base Material
by Laura Kurzendorfer-Brose and Martin Rosentritt
Materials 2025, 18(6), 1323; https://doi.org/10.3390/ma18061323 - 17 Mar 2025
Cited by 1 | Viewed by 938
Abstract
(1) Understanding the effects of manufacturing factors on microbial adhesion is essential for optimizing additive denture base materials and improving their clinical performance. This study evaluated how polymerization time, layer thickness, extended cleaning, and storage conditions influence C. albicans and S. mutans adhesion [...] Read more.
(1) Understanding the effects of manufacturing factors on microbial adhesion is essential for optimizing additive denture base materials and improving their clinical performance. This study evaluated how polymerization time, layer thickness, extended cleaning, and storage conditions influence C. albicans and S. mutans adhesion on a denture base material. (2) Specimens (n = 15/group, d = 8 mm, h = 2 mm) were additively fabricated or poured (reference). Digital light processing was performed with varying polymerization times, layer thicknesses, extended cleaning, and storage. Microbial adhesion was assessed using a luminescence assay. Surface properties were characterized by roughness (Sa/Sz), hardness, and surface free energy (SFE). Statistics: The Shapiro–Wilk test, ANOVA, Bonferroni post hoc test, and Pearson correlation (α = 0.05) were utilized. (3) Polymerization time, layer thickness, cleaning, and storage conditions significantly influenced C. albicans and S. mutans adhesion. Increased layer thickness reduced C. albicans adhesion but promoted S. mutans colonization, emphasizing the role of SFE. Extended polymerization and optimized cleaning reduced microbial adhesion, highlighting the need for tailored processing to enhance microbial resistance and material integrity. (4) Manufacturing factors influenced microbial adhesion, with additive materials reducing the abundance of C. albicans but increasing the abundance of S. mutans, underscoring the importance of material adjustments and extended polymerization to enhance microbial resistance. Full article
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16 pages, 7306 KB  
Article
Fabrication of Cu/SiC Surface Composite via Thermo-Mechanical Process (Friction Stir Processing) for Heat Sink Application
by Harikishor Kumar, Abhishek Agarwal, Michel Kalenga Wa Kalenga, Rabindra Prasad, Parshant Kumar, L. Aslesha Chilakamarri and Balram Yelamasetti
Materials 2025, 18(5), 1179; https://doi.org/10.3390/ma18051179 - 6 Mar 2025
Cited by 8 | Viewed by 2440
Abstract
For the busting of heat, generated in electronic packages, relevant materials need to be developed. Metal matrix composites may be considered as an option to tailor the properties of a material (Cu) by incorporating an additional phase (SiC) for fulfilling the requirements of [...] Read more.
For the busting of heat, generated in electronic packages, relevant materials need to be developed. Metal matrix composites may be considered as an option to tailor the properties of a material (Cu) by incorporating an additional phase (SiC) for fulfilling the requirements of thermal management systems. The composite (Cu/SiC) was manufactured by friction stir processing. For good interfacial strength, the biggest challenge in the fabrication of Cu/SiC composite was to abolish the reaction between Cu and SiC. Being solid in nature, the process (friction stir processing) does not allow temperature to reach the interfacial interaction. Scanning electron microscopy, electron backscattered diffraction, and optical microscopy were used to characterise the composite for microstructural features (particle dispersion, phases present). To confirm the presence of reinforcement, EDS analysis was also performed on the composite. Results indicated the presence of Cu and SiC phases in the stir zone (SZ) with uniform and homogeneous separation of reinforcements. The composite displayed higher hardness, tensile strength, and wear resistance in comparison to unprocessed copper. However, ductility decreased due to high hardness in the composite. Full article
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23 pages, 15646 KB  
Article
Evaluation of Surface Finishing Efficiency of Titanium Alloy Grade 5 (Ti–6Al–4V) After Superfinishing Using Abrasive Films
by Katarzyna Tandecka, Wojciech Kacalak, Michał Wieczorowski and Thomas G. Mathia
Materials 2024, 17(21), 5198; https://doi.org/10.3390/ma17215198 - 25 Oct 2024
Cited by 5 | Viewed by 20882
Abstract
Ti–6Al–4V is the most commonly used alpha–beta titanium alloy, making it the most prevalent among all titanium alloys. The processed material is widely employed in aerospace, medical, and other industries requiring moderate strength, a good strength-to-weight ratio, and favorable corrosion resistance. A microfinishing [...] Read more.
Ti–6Al–4V is the most commonly used alpha–beta titanium alloy, making it the most prevalent among all titanium alloys. The processed material is widely employed in aerospace, medical, and other industries requiring moderate strength, a good strength-to-weight ratio, and favorable corrosion resistance. A microfinishing process on the titanium alloy surface was conducted using abrasive films with grain sizes of 30, 12, and 9 μm. Superfinishing with abrasive films is a sequential process, where finishing operations are performed with tools of progressively smaller grains. The surface topography measurements of the workpiece were taken after each operation. The experiment was in the direction of developing a new surface smoothness coefficient considering the number and distribution of contact points so as to properly evaluate the quality of the surface finishing. The results showed that the finest-grain films gave the most uniform contact points, thus offering the best tribological characteristics; the 9 LF (micron lapping film) tools gave the smoothest surfaces (Sz = 2 µm), while the biggest-grain films, such as the 30 FF (micron microfinishing film), were less effective since large protrusions formed. This is a suitable study to explore the optimization paths for the superfinishing of titanium alloys, with implications for improving the performance and longevity of components in critical industrial applications. Full article
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12 pages, 1958 KB  
Article
Comparison of Optical Properties and Fracture Loads of Multilayer Monolithic Zirconia Crowns with Different Yttria Levels
by Chien-Ming Kang, Tzu-Yu Peng, Yan-An Wu, Chi-Fei Hsieh, Miao-Ching Chi, Hsuan-Yu Wu and Zih-Chan Lin
J. Funct. Biomater. 2024, 15(8), 228; https://doi.org/10.3390/jfb15080228 - 16 Aug 2024
Cited by 6 | Viewed by 3078
Abstract
Multilayer monolithic zirconia, which incorporates polychromatic layers that mimic natural tooth gradients, offers enhanced aesthetics and functionality while reducing debonding risks and improving fabrication efficiency. However, uncertainties remain regarding the fracture characteristics of multilayer monolithic zirconia crowns under occlusal loading, whether composed of [...] Read more.
Multilayer monolithic zirconia, which incorporates polychromatic layers that mimic natural tooth gradients, offers enhanced aesthetics and functionality while reducing debonding risks and improving fabrication efficiency. However, uncertainties remain regarding the fracture characteristics of multilayer monolithic zirconia crowns under occlusal loading, whether composed of uniform or combined yttria levels. The current study investigated how variations in yttria levels and thicknesses affected the optical properties and fracture loads of multilayer monolithic zirconia. Samples of multilayer monolithic zirconia in the Vita A1 shade were used, while employing 3Y (SZ) and 4Y + 5Y (AZ) yttria levels. The optical properties, including the color difference (ΔEWS) and translucency parameters (TP00), were measured using a digital colorimeter. The fracture loads were analyzed using a universal testing machine, and fractured surfaces were examined under a stereomicroscope. Statistical analyses assessed the impacts of the yttria levels and sample thicknesses on the optical properties. The ΔEWS values of SZ ranged 3.6 to 4.0, while for AZ, ΔEWS at 0.5 mm was 3.9 and <2.6 for other thicknesses. The TP00 values decreased with an increased thickness, with AZ generally exhibiting greater translucency than SZ. In the fracture load investigations, SZ (>1600 N) generally exceeded AZ (>1260 N), with fracture loads notably increasing with thickness, particularly for premolars (SZ > 3270 N, AZ > 2257 N). SZ predominantly exhibited partial and complete fractures, whereas AZ showed fewer non-fracture categorizations. Complete fractures began with dense, irregular cracks that extended outward to reveal smooth surfaces, while premolars subjected to higher loads exhibited concentric ripple-like structures. Partial fractures revealed radial textures indicative of areas of stress concentration. In summary, higher yttria levels were correlated with increased translucency, while variations in the fracture loads primarily stemmed from differences in the tooth position or thickness. Overall, multilayer monolithic zirconia incorporating combined yttria levels of 4Y + 5Y (AZ) offered high translucency, precise color matching, and substantial fracture resistance, rendering it highly suitable for aesthetic and functional dental applications. Full article
(This article belongs to the Special Issue Advances in Restorative Dentistry Materials)
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28 pages, 11931 KB  
Article
Chloride-Induced Stress Corrosion Cracking of Friction Stir-Welded 304L Stainless Steel: Effect of Microstructure and Temperature
by Anirban Naskar, Madhumanti Bhattacharyya, Saumyadeep Jana, Jens Darsell, Krishnan S. Raja and Indrajit Charit
Crystals 2024, 14(6), 556; https://doi.org/10.3390/cryst14060556 - 16 Jun 2024
Cited by 5 | Viewed by 3216
Abstract
Dry storage canisters of used nuclear fuels are fabricated using SUS 304L stainless steel. Chloride-induced stress corrosion cracking (CISCC) is one of the major failure modes of dry storage canisters. The cracked canisters can be repaired by friction stir welding (FSW), a low-heat [...] Read more.
Dry storage canisters of used nuclear fuels are fabricated using SUS 304L stainless steel. Chloride-induced stress corrosion cracking (CISCC) is one of the major failure modes of dry storage canisters. The cracked canisters can be repaired by friction stir welding (FSW), a low-heat input ‘solid-phase’ welding process. It is important to evaluate the ClSCC resistance of the friction stir welded material. Stress corrosion cracking (SCC) studies were carried out on mill-annealed base materials and friction stir welded 304L stainless U-bend specimens in 3.5% NaCl + 5 N H2SO4 solution at room temperature and boiling MgCl2 solution at 155 °C. The engineering stress on the outer fiber of the FSW U-bend specimen was ~60% higher than that of the base metal (BM). In spite of the higher stress level of the FSW, both materials (FSW and BM) showed almost similar SCC failure times in the two different test solutions. The SCC occurred in the thermo-mechanically affected zone (TMAZ) of the FSW specimens in the 3.5% NaCl + 5 N H2SO4 solution at room temperature, while the stirred zone (SZ) was relatively crack-free. The failure occurred at the stirred zone when tested in the boiling MgCl2 solution. Hydrogen reduction was the cathodic reaction in the boiling MgCl2 solution, which promoted hydrogen-assisted cracking of the heavily deformed stirred zone. The emergence of the slip step followed by passive film rupture and dissolution of the slip step could be the SCC events in the 3.5% NaCl + 5 N H2SO4 solution at room temperature. However, the slip step height was not sufficient to cause passivity breakdown in the fine-grained SZ. Therefore, the SCC occurred in the partially recrystallized softer TMAZ. Overall, the friction-stirred 304L showed higher tolerance to ClSCC than the 304L base metal. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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Article
Quasi-In Situ Observation of the Microstructural Response during Fatigue Crack Growth of Friction Stir Welded AA2024-T4 Joint
by Jun Yang, Xianmin Chen, Huaxia Zhao, Jihong Dong and Feng Jin
Materials 2024, 17(9), 2106; https://doi.org/10.3390/ma17092106 - 29 Apr 2024
Cited by 1 | Viewed by 1822
Abstract
The reliability of friction stir welded joints is a critical concern, particularly given their potential applications in the aerospace manufacturing industry. This study offers a quasi-in situ observation of the microstructural response during fatigue crack growth (FCG) of a friction stir welded AA2024-T4 [...] Read more.
The reliability of friction stir welded joints is a critical concern, particularly given their potential applications in the aerospace manufacturing industry. This study offers a quasi-in situ observation of the microstructural response during fatigue crack growth (FCG) of a friction stir welded AA2024-T4 joint, aiming to correlate fatigue crack growth behavior with mechanical properties investigated using electron backscatter diffraction (EBSD). Notched compact tension (CT) specimens corresponding to the morphology of the stir zone (SZ), advancing side (AS), and retreating side (RS) were meticulously designed. The findings indicate that the welding process enhances the joint’s resistance to fatigue crack growth, with the base metal exhibiting a shorter fatigue life (i.e., ~105 cycles) compared to the welding zones (SZ ~ 3.5 × 105 cycles, AS ~ 2.5 × 105 cycles, and RS ~ 3.0 × 105 cycles). Crack propagation occurs within the stir zone, traversing refined grains, which primarily contribute to the highest fatigue life and lowest FCG rate. Additionally, cracks initiate in AS and RS, subsequently expanding into the base metal. Moreover, the study reveals a significant release of residual strain at the joint, particularly notable in the Structural-CT-RS (Str-CT-RS) sample compared to the Str-CT-AS sample during the FCG process. Consequently, the FCG rate of Str-CT-AS is higher than that of Str-CT-RS. These findings have significant implications for improving the reliability and performance of aerospace components. Full article
(This article belongs to the Special Issue Advances in Solid-State Welding Processes)
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