Effect of heat treatment on hydrogen storage properties and thermal stability of V68Ti20Cr12 alloy

Effect of heat treatment on the crystal structure, microstructure, hydrogen storage properties and thermal stability of V68Ti20Cr12 alloy prepared by arc-melting was studied in this work. It was found that both the as-cast and annealed (973 K/72 h) V68Ti20Cr12 alloys consisted of a single body-centered cubic (bcc) phase. After heat treatment, the hydrogen absorption/desorption kinetic characteristics of the as-cast alloy was improved greatly due to the homogeneous composition and perfect structure. The mechanism of hydrogen absorption/desorption process in the as-cast and annealed alloys was further investigated according to the Johnson-Mehl-Avrami (JMA) equation. The hydrogen absorption process of the as-cast and annealed alloys would be controlled by the one-dimensional diffusion process, while the hydrogen desorption process in the as-cast and annealed alloys was dominated by the geometrical contraction model. The pressure-composition-temperature (PCT) measurements show that the plateau pressure of the annealed alloy becomes comparatively flat. Furthermore, the activation energies of the dehydrogenation in the as-cast and annealed alloys were calculated using the Kissinger method, indicating that heat treatment is a very beneficial way to improve hydrogen absorption/desorption kinetics of the alloy. Keywords: V-Ti-Cr alloys, Hydrogen storage properties, Thermal stability, Heat treatmen

Influence of Zr Addition on the Microstructure and Hydrogenation Kinetics of Ti_50−xV₂₅Cr₂₅Zr_x (x = 0, 5, 7, and 9) Alloys

Due to the poor activation performance and kinetics of Ti50V25Cr25 alloys, the element Zr was added to improve the phase structure of the alloy and achieve a high-performance hydrogen storage alloy. The Ti50−xV25Cr25Zrx (x = 0, 5, 7, and 9) system alloys were prepared by arc melting. The alloys were analyzed using an X-ray diffractometer (XRD), scanning electron microscope (SEM), and differential scanning calorimeter (DSC). The hydrogen storage capabilities of the alloys were also obtained by the Sievert volumetric method. The results indicated that the alloy with Zr added had a combination of the C15 Laves phase and the BCC phase, whereas the Zr-free alloy had a BCC single phase. The partial replacement of Zr with Ti resulted in an increase in the lattice parameters of the main phase. The hydrogen storage kinetic performance and activation of the alloys both significantly improved with an increasing Zr concentration. The time to reach 90% of the maximum hydrogen storage capacity decreased to 2946 s, 230 s, and 120 s, respectively, with the increases in Zr concentration. The initial hydrogen absorption content of the alloys increased and then decreased after the addition of the element Zr. The second phase expanded with an increasing Zr concentration, which in turn decreased the abundance of the BCC main phase. The Ti43V25Cr25Zr7 alloy showed good cycle stability and hydrogen-desorption performance, and it could absorb 90% of the maximum hydrogen storage capacity in around 230 s. The maximum hydrogen-absorption capacity of the alloy was 2.7 wt%. The diffusion activation energy of hydrogen desorption dropped from 102.67 kJ/mol to 92.62 kJ/mol

Advancements in tissue engineering for articular cartilage regeneration

Articular cartilage injury is a prevalent clinical condition resulting from trauma, tumors, infection, osteoarthritis, and other factors. The intrinsic lack of blood vessels, nerves, and lymphatic vessels within cartilage tissue severely limits its self-regenerative capacity after injury. Current treatment options, such as conservative drug therapy and joint replacement, have inherent limitations. Achieving perfect regeneration and repair of articular cartilage remains an ongoing challenge in the field of regenerative medicine. Tissue engineering has emerged as a key focus in articular cartilage injury research, aiming to utilize cultured and expanded tissue cells combined with suitable scaffold materials to create viable, functional tissues. This review article encompasses the latest advancements in seed cells, scaffolds, and cytokines. Additionally, the role of stimulatory factors including cytokines and growth factors, genetic engineering techniques, biophysical stimulation, and bioreactor systems, as well as the role of scaffolding materials including natural scaffolds, synthetic scaffolds, and nanostructured scaffolds in the regeneration of cartilage tissues are discussed. Finally, we also outline the signaling pathways involved in cartilage regeneration. Our review provides valuable insights for scholars to address the complex problem of cartilage regeneration and repair

Flooding Depth and Flooding Duration with the Zonation of Riparian Plant Communities in the Three Gorges Reservoir of China

The hydraulics of flows, especially the flooding process, influence the patterns of riparian plant zonation. Different characteristics of the flooding process should be analyzed to correlate plant zonation with flooding due to their different effect modes. The effects of flooding characteristics on riparian plants have yet to be studied, especially in the field. Thus, two elements of the flow regime, flooding duration and depth, were analyzed in relation to the riparian plants of the Three Gorges Reservoir. The taxonomic indices and the functional diversity of the riparian plants in three seasons in 2019 and the corresponding inundation character were surveyed. Our results showed that the riparian plant diversity and functional diversity varied by season. A significant negative relationship between plant diversity and flooding depth was observed, while flooding duration was not a significant predictor in different seasons. The greater explanatory capacity of flooding depth than that of flooding duration suggests that flooding depth could be a better indicator of the zonation of the riparian vegetation in this area. Concerning the vital component of flow hydraulics, growing opportunities to study flooding depth and strategies that consider both flooding time and flooding depth in a reservoir should be offered, as they will assist in refining process-based river restoration

Phase Formation, Microstructure, and Magnetic Properties of Nd14.5Fe79.3B6.2 Melt-Spun Ribbons with Different Ce and Y Substitutions

Phase formation and microstructure of (Nd1-2xCexYx)14.5Fe79.3B6.2 (x = 0.05, 0.10, 0.15, 0.20, 0.25) alloys were studied experimentally. The results reveal that (Nd1-2xCexYx)14.5Fe79.3B6.2 annealed alloys show (NdCeY)2Fe14B phase with the tetragonal Nd2Fe14B-typed structure (space group P42/mnm) and rich-RE (α-Nd) phase, while (Nd1-2xCexYx)14.5Fe79.3B6.2 ribbons prepared by melt-spun technology are composed of (NdCeY)2Fe14B phase, α-Nd phase and α-Fe phase, except for the ribbon with x = 0.25, which consists of additional CeFe2 phase. On the other hand, magnetic properties of (Nd1-2xCexYx)14.5Fe79.3B6.2 melt-spun ribbons were measured by a vibrating sample magnetometer (VSM). The measured results show that the remanence (Br) and the coercivity (Hcj) of the melt-spun ribbons decrease with the increase of Ce and Y substitutions, while the maximum magnetic energy product ((BH)max) of the ribbons decreases and then increases. The tendency of magnetic properties of the ribbons could result from the co-substitution of Ce and Y for Nd in Nd2Fe14B phase and different phase constitutions. It was found that the Hcj of the ribbon with x = 0.20 is relatively high to be 9.01 kOe, while the (BH)max of the ribbon with x = 0.25 still reaches to be 9.06 MGOe. It suggests that magnetic properties of Nd-Fe-B ribbons with Ce and Y co-substitution could be tunable through alloy composition and phase formation to fabricate novel Nd-Fe-B magnets with low costs and high performance

Detection of Famous Tea Buds Based on Improved YOLOv7 Network

Aiming at the problems of dense distribution, similar color and easy occlusion of famous and excellent tea tender leaves, an improved YOLOv7 (you only look once v7) model based on attention mechanism was proposed in this paper. The attention mechanism modules were added to the front and back positions of the enhanced feature extraction network (FPN), and the detection effects of YOLOv7+SE network, YOLOv7+ECA network, YOLOv7+CBAM network and YOLOv7+CA network were compared. It was found that the YOLOv7+CBAM Block model had the highest recognition accuracy with an accuracy of 93.71% and a recall rate of 89.23%. It was found that the model had the advantages of high accuracy and missing rate in small target detection, multi-target detection, occluded target detection and densely distributed target detection. Moreover, the model had good real-time performance and had a good application prospect in intelligent management and automatic harvesting of famous and excellent tea

Thermodynamic Modeling of the Ag-Cu-Sn Ternary System

In this work, combined with previous assessments of the Ag-Cu, Ag-Sn and Cu-Sn binary systems, thermodynamic modeling of the Ag-Cu-Sn ternary system was performed using the CALPHAD method using the reported phase diagram data and thermodynamic data. The solution phases including Liquid, fcc, bcc, hcp, bct(Sn) and diamond(Sn) were modeled as substitutional solutions and their excess Gibbs energies were expressed by the Redlich–Kister–Muggianu polynomial. The solubility of the third element in binary intermetallic compounds was not taken into account due to the fact that ternary solubilities for most of the binary compounds are not significant. Thermodynamic properties of liquid alloys, liquidus projection, several vertical sections and isothermal sections were calculated, which were in reasonable agreement with the reported experimental data. Finally, a set of self-consistent thermodynamic parameters formulating the Gibbs energies of various phases in the Ag-Cu-Sn ternary system was obtained

Thermodynamic Modeling of the Ag-Cu-Sn Ternary System

In this work, combined with previous assessments of the Ag-Cu, Ag-Sn and Cu-Sn binary systems, thermodynamic modeling of the Ag-Cu-Sn ternary system was performed using the CALPHAD method using the reported phase diagram data and thermodynamic data. The solution phases including Liquid, fcc, bcc, hcp, bct(Sn) and diamond(Sn) were modeled as substitutional solutions and their excess Gibbs energies were expressed by the Redlich–Kister–Muggianu polynomial. The solubility of the third element in binary intermetallic compounds was not taken into account due to the fact that ternary solubilities for most of the binary compounds are not significant. Thermodynamic properties of liquid alloys, liquidus projection, several vertical sections and isothermal sections were calculated, which were in reasonable agreement with the reported experimental data. Finally, a set of self-consistent thermodynamic parameters formulating the Gibbs energies of various phases in the Ag-Cu-Sn ternary system was obtained

Phase formation and magnetic properties of (Nd1−xYx)14Fe80B6 melt-spun ribbons

Phase formation and magnetic properties of (Nd _1−x Y _x ) _14 Fe _80 B _6 (x = 0.1–0.8) alloys were investigated experimentally by x-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The phase structure analysis reveals that the as-cast (Nd _1−x Y _x ) _14 Fe _80 B _6 alloys were made of 2:14:1 phase with tetragonal Nd _2 Fe _14 B-tpyed structure, REFe _2 and α -Fe phases, while the melt-spun ribbons are composed of 2:14:1 phase and α -Fe Phase. Based on the magnetic measurements, the remanence (B _r ), the coercivity (H _cj ), the maximum magnetic energy product ((BH) _max ) and the Curie temperatures (T _c ) of (Nd _1−x Y _x ) _14 Fe _80 B _6 ribbons reduces gradually with increasing Y substitution. The relatively high coercivity (6.75 kOe) of (Nd _0.4 Y _0.6 ) _14 Fe _80 B _6 ribbon with high Y substitution was achieved, which indicates that good magnetic properties of Nd–Y–Fe–B ribbons would be obtained through the design of alloy composition and phase formation