Search Results (12,783)

The nanoindentation analysis of zirconium carbide (ZrC) has been studied through molecular dynamics simulations, focusing on various factors such as temperature, stoichiometric ratio, and crystal orientation. The findings show that as temperature increases, both the critical pop-in load and the maximum load decrease, while atomic strain, von Mises stress, and residual indentation depth increase. High temperatures facilitate the nucleation and propagation of 1/2<110> dislocations, which enhance the material’s ability to undergo plastic deformation. Both indentation hardness and Young’s modulus decrease linearly as temperature rises or the concentration of C vacancy increases. For stoichiometric ZrC, as the temperature rises from 10 K to 2100 K, the hardness decreases from 45.04 GPa to 20.36 GPa, and Young’s modulus drops from 396.28 GPa to 254.45 GPa. At 10 K, when the C/Zr ratio is reduced to 0.5, the hardness and Young modulus decrease to 25.32 GPa and 192.09 GPa, respectively. This reduction is attributed to the weakening of Zr-C bonds, which also reduces stress concentration. At elevated temperatures, the impact of C vacancies on the nanoindentation process diminishes due to the thermal softening of the substrate, which lessens the effects of vacancy-induced softening. Regarding anisotropy, Young’s modulus at room temperature decreases from 383.39 GPa on the (001) plane to 335.93 GPa on the $(1\stackrel{\mathrm{-}}{1}0)$ plane, and it reduces further to 303.31 GPa on the $(1\stackrel{\mathrm{-}}{1}1)$ plane; hardness shows a similar decreasing trend. This trend is primarily due to differences in slip systems, surface energies, and the angles between the plane normal and the Zr-C bond axis located directly beneath the surface atoms. Overall, these results may provide theoretical support for the processing and application of ZrC. Full article

Selenophosphates and tellurophosphates are important classes of organophosphorus compounds that exhibit unique reactivity, tunable redox properties, and significant biological activity. Herein, we report a mild and efficient Mn(III)-catalyzed method for synthesizing selenophosphates and tellurophosphates. Using Mn(OAc)₃ as the catalyst and tetrahydrofuran (THF) as the solvent, various H-phosphonates and H-phosphine oxides undergo radical coupling with diselenides or ditellurides at room temperature in the presence of air, affording good-to-excellent yields of the corresponding chalcogenophosphates. The protocol features a broad substrate scope, favorable functional group tolerance, and low catalyst loading while avoiding the use of toxic reagents or strong oxidants. Mechanistic studies suggest that the reaction proceeds via the phosphinyl radicals generated through single-electron oxidation mediated by Mn(III). Full article

GH4141 + 0.2 wt.% Y₂O₃ superalloy was fabricated using laser powder bed fusion (LPBF) technology and subjected to solution and ageing heat treatments. The effects of laser power (1100, 1300, 1500 W) on the microstructure and mechanical properties of the ODS nickel-based superalloy were investigated. The results indicate that as the laser power increased from 1100 W to 1300 W, defects such as cracks and pores in the specimens decreased, the grains were refined, and the microstructure became more uniform; when the laser power was further increased to 1500 W, the grain size coarsened significantly, precipitation phases at the grain boundaries became coarser or locally aggregated, and crack sensitivity increased. EDS analysis revealed enrichment of C, Cr, Mo and Ti in the dark phases at the grain boundaries, which may be associated with MC-type and M₂₃C₆-type carbides; no significant agglomeration of Y₂O₃ particles was observed in the matrix. Room-temperature tensile properties exhibited a pattern of initially increasing and then decreasing with increasing laser power. The tensile strength and elongation after fracture of the specimens were relatively similar under 1100 W and 1500 W conditions, whilst the specimen tested at 1300 W achieved the optimal balance of strength and toughness, with a tensile strength of 1460 MPa and an elongation after fracture of 14.3%, representing increases of approximately 9.8% and 54% compared to the 1100 W and 1500 W conditions, respectively. At 760 °C, the 1300 W specimens still maintained excellent high-temperature strength. Full article

Elastic springback is a critical challenge in sheet metal bending that directly affects dimensional accuracy and manufacturing efficiency. This study presents a comparative experimental and machine learning-based analysis of elastic springback behavior in three widely used sheet metals like stainless steel, aluminum, and copper, which are subjected to folding bending. The influence of key process parameters, namely sheet thickness (0.5 to 1.5 mm) and bending temperature (room temperature to 200 °C), was systematically examined under cold working. A cost-effective localized heating approach using a direct flame was introduced to enhance process control and reduce elastic recovery without the complexity associated with heated dies. Experimental results revealed substantial variability in elastic springback, ranging from 0.15% to 12.41%, emphasizing the fact that they are nonlinear in nature. Statistical evaluation confirmed that sheet thickness is the dominant factor governing elastic springback, while material type and temperature exhibit secondary yet meaningful effects. To improve predictive capability, five regression models (Linear, Polynomial, Support Vector, Random Forest, and Gradient Boosting) were developed and assessed. Among them, Random Forest demonstrated superior performance with the lowest prediction errors and strongest explanatory power, achieving an R² of approximately 0.85. Cross-validation further validated its robustness and generalization capability. Feature importance and SHapley Additive exPlanations (SHAP) analyses reinforced the primary role of thickness in determining elastic recovery behavior. The findings provide practical insights for selecting materials and process conditions to minimize elastic springback while highlighting the effectiveness of ensemble learning techniques for accurate prediction. This work contributes a consistent framework for enhancing bending precision and supports data-driven decision-making in modern manufacturing environments. Full article

Background/Objectives: In case of EDTA-induced pseudothrombocytopenia (PTCP), MgSO₄-anticoagulated tubes are recommended for platelet counting, requiring the collection of an additional tube. The aim of this study was to analyze whether complete blood count (CBC) and differential performed on MgSO₄-anticoagulated tubes were comparable to the results obtained on K₃-EDTA samples, and to characterize the stability of the CBC over a 24 h period. Methods: In 355 patients (70 with a confirmed PTCP and 285 without PTCP), we compared CBC results obtained on K₃-EDTA- and MgSO₄-anticoagulated tubes, using DxH800 analyzers. In 33 cases, a differential was available for both anticoagulants, and for 10 patients, samples were re-analyzed 6, 12, and 24 h after the first determination. Results: In the presence or absence of clumps, white blood cell (WBC) count, hematocrit, and mean corpuscular volume (MCV) were slightly lower in MgSO₄ than in K₃-EDTA tubes, whereas mean corpuscular hemoglobin concentration (MCHC) was slightly higher. Mean platelet volume (MPV) was significantly lower on MgSO₄- than on K₃-EDTA-anticoagulated tubes. Values were highly correlated between both anticoagulants, and mean relative biases (MRBs) were below Ricos’s recommendations, except for MCHC and MPV. For differential, neutrophils were significantly lower on MgSO₄- in comparison to K₃-EDTA-anticoagulated tubes (MRB = −2.9%, below Ricos’s optimal bias). The morphology of white blood cells (WBCs) was similar on both anticoagulants. During storage at room temperature, MCV and red cell distribution width increased slightly, but the increase was more pronounced in K₃-EDTA than in MgSO₄ tubes. Conclusions: CBC and differentials obtained with the DxH 800 analyzer on MgSO₄-anticoagulated samples are similar to those obtained with K₃-EDTA, except for MPV. Full article

This paper presents a comprehensive evaluation of control strategies for a highly energy-efficient plus-energy terraced housing complex equipped with photovoltaic generation, modulating ground-source heat pumps, electrical and thermal energy storage systems, and activation of building thermal mass. The study combines long-term monitoring data, annual simulations, and hardware-in-the-loop (HiL) experiments to assess modulating heat-controlled operation (HC), PV-controlled (PVC), and predictive control strategies, including simple predictive control (SPC) and model predictive control (MPC). The simulation results show that the baseline HC operation already achieves a high load cover factor (LCF), defined as the fraction of total electrical demand covered by local PV generation (direct use + battery discharge) of 65.6% and a seasonal performance factor (SPF) of the central heat pumps of 5.8. PVC increases LCF (71.0%) by shifting heat pump operation toward PV-rich periods but leads to elevated storage temperatures up to 5 K and a reduced SPF of 4.8. MPC further enhances LCF by 4–7 percentage points in simulated and HiL environments. However, its real-world performance is strongly influenced by forecast quality and the limited controllability of the heat pump system. In addition, building thermal mass activation is investigated as a complementary flexibility option. Simulation and monitoring results demonstrate that moderate room temperature set-point (2 K) increases during PV availability significantly improve LCF from 20% to 55% while maintaining thermal comfort. Overall, the findings indicate that in highly efficient plus-energy buildings, robust rule-based strategies combined with thermal mass activation can achieve a large share of the attainable benefits, while the added complexity of MPC must be carefully weighed against practical limitations. Full article

Background/Objectives: Ursodeoxycholic acid (UDCA) is a bile acid widely used for the treatment of cholestatic liver diseases; however, its poor aqueous solubility represents a major limitation for the development of oral liquid formulations, particularly in pediatric patients requiring accurate and flexible dosing. This study aimed to develop and characterize a fully solubilized extemporaneous UDCA oral formulation using the ready-to-use vehicle Wagner, with particular emphasis on the role of hydroxypropyl-β-cyclodextrin (HP-β-CD) as a solubilizing excipient. Methods: Phase-solubility studies, Job’s plot analysis, and ¹H NMR spectroscopy were performed to investigate the host–guest interaction between UDCA and HP-β-CD, confirming the formation of a stable 1:1 inclusion complex responsible for a marked increase in drug solubility. The aqueous solubility of UDCA increased from approximately 0.02 mg/mL in water to 31 ± 1 mg/mL in the Wagner base containing HP-β-CD, compared to ~10 mg/mL in the corresponding cyclodextrin-free vehicle. Chemical stability was evaluated using an HPLC method adapted from the European Pharmacopoeia, employing dual detection (refractive index and photodiode array detector) to ensure specificity and stability-indicating capability. Results: The UDCA solution (20 mg/mL) remained chemically stable for at least 4 months under refrigerated (4–8 °C) and room temperature (25 °C) conditions, with only moderate degradation observed at 40 °C. Physical stability studies confirmed the absence of precipitation, phase separation, or significant pH variations under all storage conditions. Conclusions: Wagner-based formulation enabled the development of a stable and homogeneous UDCA oral solution, providing a complementary formulation strategy to conventional suspension-based preparations. This approach represents a robust and patient-oriented strategy for extemporaneous compounding, particularly suitable for pediatric use. Full article

TC2 titanium alloy (Ti-4Al-1.5Mn, wt.%) is a near-α titanium alloy with promising aerospace and biomedical applications, but its limited room temperature ductility and strong texture sensitivity hinder the fabrication of high-performance sheets. In this study, the effects of hot rolling at 830 °C and 930 °C on the microstructure, macro-texture, mechanical properties, and fracture behavior of TC2 alloy were investigated. Compared with the 830 °C rolled sample, the 930 °C rolled sample exhibited finer primary α grains, a higher volume fraction of fine and dispersed secondary α_s phase, and more uniform Mn distribution, while both samples retained an α + β phase constitution. Texture and ODF (orientation distribution function) analyses revealed that increasing the rolling temperature reduced the maximum intensity of the (0001) pole figure from 6.68 to 5.23 m.r.d. (multiples of a random distribution) and increased that of the (10-10) pole figure to 9.62 m.r.d., indicating weakened basal texture, enhanced prismatic texture, and more dispersed orientation distribution. Consequently, although the tensile strength slightly decreased to approximately 730 MPa, the elongation increased from approximately 24% to 28%. The finer and denser dimples observed after 930 °C rolling further confirmed improved plastic deformation coordination. Full article

The extreme thermal environment during the underground coal gasification (UCG) process poses a severe threat to the stability of the gasification cavity and the integrity of the surrounding rock. This paper aims to reveal the thermo-mechanical response characteristics and damage evolution mechanism of sandstone under true triaxial unloading conditions following exposure to high temperatures. Sandstone specimens were thermally pre-treated at five temperature gradients (25 °C, 200 °C, 400 °C, 600 °C, and 800 °C) and subsequently subjected to true triaxial loading and unloading experiments. The effects of varying temperatures on the strength, deformation parameters, dilation angle evolution, and macroscopic failure modes of the sandstone were systematically analyzed. The results indicate a significant critical transition point in the mechanical behavior of the sandstone at 400 °C. Below this threshold, thermal-induced microcrack closure leads to an increase in peak strength (with the peak strength at 800 °C increasing by approximately 67% compared to room temperature). Conversely, above 400 °C, thermal damage to the mineral grains intensifies, causing the crack propagation pattern to transition from brittle shear to a complex tension-shear splitting mode, accompanied by severe dilatancy (with a generalized Poisson’s ratio exceeding 0.8). Based on these findings, this study proposes a stage-wise damage evolution model alongside a targeted zonal support strategy, recommending the application of high-prestressed support in high-temperature zones above 400 °C to suppress tensile failure. Ultimately, this research provides a crucial theoretical basis for evaluating the long-term stability of high-temperature underground engineering projects and ensuring operational safety. Full article

Scandium (Sc) is well recognized as a potent grain refiner, yet optimizing its addition amount in the Al-Cu-Mg-Ni-Fe (A242) system remains a longstanding challenge, critically important for material performance in high-temperature automotive and aerospace applications. The present work, therefore, presents a study of low-Sc modified A242 alloys, demonstrating that 0.2 wt.% Sc microalloying of the system has a pronounced effect on its solidification-driven microstructural evolution, improving the high-temperature formability of the alloy over a 20–200 °C temperature range. The study demonstrates that this addition triggers a dramatic columnar-to-equiaxed grain transition, reducing the average grain size by 90.8% (from 400 ± 100 μm to 37 ± 10 μm) and fragmenting the brittle, continuous intermetallic network into a highly uniform architecture. Uniaxial compression testing revealed that, while the as-cast solid-solution alloy slightly reduces room-temperature strength due to solute trapping, it delivers an exceptional 142% increase in strain-to-failure at 200 °C (exceeding 0.8 mm) compared to the base alloy. This significant enhancement in ductility is driven by thermally stable Al₃Sc dispersoids that exert Zener pinning pressure, halting thermal grain coarsening and activating superplastic deformation mechanisms. These findings support the development of advanced thermoforming applications, with the finite element (FE) model predicting process improvements that enhance manufacturing efficiency. This work presents a validation and simulation-ready material framework that substantiates the viability of low-Sc-modified A242 alloys for such operations. Full article

Addressing the urgent demand for high-precision pressure measurement in real-time barometric monitoring, aerospace, and industrial control, this paper presents a high-accuracy MEMS resonant pressure sensor based on electrostatic excitation and piezoresistive detection. The sensor incorporates a symmetric double-ended fixed-finger comb-drive resonator structure, driven into stable vibration at its natural frequency by an alternating electrostatic force. Piezoresistors integrated at the root of the resonant beams transduce the mechanical vibration into a frequency output, enabling precise external pressure measurement. Experimental results show that the developed sensor achieves an accuracy of 0.009% FS over a pressure range of 0–350 kPa across an operating temperature span from −30 °C to 50 °C, with a room-temperature repeatability error below 0.008% FS, demonstrating excellent measurement stability. Building on this performance, a real-time atmospheric pressure monitoring experiment was conducted, yielding a mean absolute percentage error of less than 0.05%, highlighting the sensor’s potential for engineering practicality. This work provides an effective technique for a high-precision, high-stability resonant pressure sensor, with clear potential for deployment in real-time barometric monitoring, aerospace, and industrial control applications. Full article

Ready-to-eat sea cucumbers (RSC) cannot be preserved at room temperature due to autolysis, which is closely related to the instability of collagen resulting from the disruption of hydrogen bonds. To investigate the protective effect of N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) cross-linking against disruption of hydrogen bonds and its role in stabilizing RSC quality at room temperature, this study designed comparative experiments involving EDC/NHS cross-linking treatments with varying sequences of hydrogen bonds disruption. The results indicated that EDC/NHS positively affects the stabilization of the collagen structure in RSC. The various quality parameters of both groups of RSC that underwent cross-linking treatment before and after hydrogen bonds disruption were significantly better than those of the control group, which only experienced the breaking of hydrogen bonds. Notably, the Eb group, which underwent EDC/NHS cross-linking treatment prior to the disruption of the hydrogen bonds network, yielded even more favorable results. Preliminary analyses of textural properties and moisture content suggested that EDC/NHS helps delay the deterioration of RSC quality. The levels of soluble components and carbonyl groups indicated that prior cross-linking treatment is more effective in mitigating collagen degradation and oxidation. Differential scanning calorimetry revealed that the reduction in ΔH for the Eb group was only 2.4%. Furthermore, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and circular dichroism spectroscopy, examined from the perspectives of secondary and tertiary structures respectively, indicated that the cross-linking mechanism of EDC/NHS involves the formation of a more robust network of amide bonds, thereby preventing the disruption of hydrogen bonds and enhancing collagen stability, enabling it to better resist the cleavage of hydrogen bonds due to urea. The scanning electron microscope and Van Gieson’s staining techniques offer a clearer illustration of this point from a microscopic perspective. Moreover, molecular docking simulations have indicated the cross-linking mechanism of EDC/NHS at the atomic level, thereby establishing a scientific foundation for the potential application and development of EDC/NHS in room-temperature storage technologies for RSC. Full article

The optimization of Fused Filament Fabrication (FFF) process parameters is commonly performed using room-temperature mechanical properties as the main decision criteria, while the temperature-dependent thermomechanical response of printed polymers is often not explicitly considered. This limitation is relevant for functional components intended to operate above room temperature, where stiffness retention and viscoelastic behavior may strongly affect service performance. This work proposes an experimental–statistical framework for selecting FFF parameters by integrating Design of Experiments (DoE), tensile testing, dynamic mechanical analysis (DMA), Analysis of Variance (ANOVA), the Entropy Weight Method (EWM) and the VIKOR method. Two materials with contrasting thermomechanical behavior were investigated: a high-performance semicrystalline polymer, Z-PEEK, and an elastomeric thermoplastic, TPU 95A. For each material, a DoE was defined to evaluate the influence of key printing parameters, and the manufactured specimens were characterized in terms of maximum tensile force, maximum deformation and storage modulus at selected temperatures. The ANOVA results showed a material-dependent influence of the processing parameters, with thermally driven parameters being especially relevant for Z-PEEK and deposition-related parameters having a stronger influence on TPU 95A. The EWM–VIKOR analysis identified the optimal Z-PEEK configuration as 400 °C extrusion temperature, 200 °C build plate temperature and 150 °C chamber temperature, whereas the optimal TPU 95A configuration corresponded to 225 °C extrusion temperature, 0.10 mm layer height, 50 mm/s printing speed and 80 °C build plate temperature. Overall, the results demonstrate that incorporating DMA-derived thermomechanical indicators into MCDM-based optimization provides a more application-oriented basis for FFF parameter selection than approaches based only on room-temperature mechanical properties. Full article

Lead-based alloy has received widespread attention as a coolant in nuclear reactors. However, there is limited research on pure lead after solidification. In this study, a systematic investigation was conducted on the long-term evolution of the microstructure and physical properties of pure lead samples solidified under different cooling rates, with a comparative analysis against of lead–bismuth eutectic (LBE). Microscopic detection (using optical and electron microscopes), density measurement, and compressive mechanical testing were carried out. The study results show that during the long-term evolution process after solidification (at room temperature of 27 °C), pure lead samples spontaneously undergo recovery and recrystallization, with larger grain size and more uniform microstructure. The density of samples remains within a stable range. The yield strength of samples after solidification will gradually decrease over time. For example, after 180 days of evolution, the yield strength of the rapidly cooled sample (10 K/min) decreased from 4.879 MPa to 3.766 MPa. Full article

Three-dimensional (3D) cardiac models, including spheroids, organoids, and organ-on-chips, are advanced systems for studying human physiology, disease, and drug responses with greater biological relevance than 2D models. As their use expands in biomedical research, tissue engineering, and regenerative medicine, reliable preservation methods are needed. However, cryopreservation often fails to protect 3D systems due to limited cryoprotectant penetration, ice formation, and mechanical stress during freezing and thawing. Room-temperature (RT) preservation has emerged as a promising alternative for short-term transport. This study evaluated a RT-based transport medium (CellShip^®) for preserving cardiac organoids for up to seven days, compared with conventional cryopreservation using slow-freezing in Cryostor^®CS10. Viability and functionality were assessed using apoptosis, ATP levels, beating activity, proliferation, and size. During maturation, organoids showed increased size, ATP levels, and beating capacity. Cryopreservation reduced size, proliferation, ATP levels, and altered beating, while increasing apoptosis. In contrast, RT preservation maintained stable viability and functionality after recovery. These findings demonstrate that RT preservation effectively maintains cardiac organoid integrity and function, offering a promising alternative for short-term storage and transport, with potential terrestrial and nonterrestrial applications. Full article