Search Results (100)

Recrystallization is a critical process for tailoring the microstructure to enhance the mechanical properties of alloys. In duplex-phase alloys, the recrystallization is different due to the influence of the second phase. Hypo-eutectic high-entropy alloys (HEAs) with two phases are promising structural materials. Understanding the laws of microstructure and mechanical properties during recrystallization is essential for fabrication and application. Here, we systematically investigate the influence of recrystallization time on the microstructure and mechanical properties of an as-cast hypo-eutectic high-entropy alloy (HEA), Al₁₃Ni₃₆Cr₁₀Fe₄₀Mo₁. As the recrystallization time increases from 10 min to 8 h at 1100 °C, the cold-rolled alloy gradually completed the recrystallization process with a residual large B2 phase and equiaxed FCC grains decorated with B2 precipitation. The average grain size of the FCC phase increases slightly from 2.60 μm to 3.62 μm, while the fine B2 phase precipitates along the FCC phase’s grain boundaries. This optimized microstructure significantly improves the alloy’s tensile strength from 422 MPa to 877 MPa, while maintaining a substantial plasticity of 41%, achieving an excellent strength–ductility balance. These findings provide useful information for regulating the industrial thermomechanical treatment of dual-phase hypo-eutectic high-entropy alloys. Full article

This study explores the sustainability of Islamic decorative arts by examining the symbolic, cultural, and spiritual dimensions of botanical decorations in Makkah’s architectural heritage. Grounded in Carl Jung’s theory of the collective unconscious and Lamya Al-Faruqi’s philosophy of Tawhid, the research uncovers the profound psychological and spiritual meanings embedded in these motifs. Employing a qualitative methodology, the study integrates symbolic analysis, cultural interpretation, and historical documentation, supported by digital design tools, to assess the relevance of these decorations in contemporary urban contexts. Findings reveal that botanical motifs, such as palm trees and pinecones, reflect universal archetypes of resilience and growth while symbolising divine unity through abstraction and harmony. The research highlights their integral role in architectural structures and their potential in cultural tourism and educational initiatives. However, challenges such as urbanisation necessitate urgent documentation and innovative preservation strategies. This study offers valuable insights into sustaining Makkah’s architectural identity by bridging psychological and philosophical perspectives. Its recommendations align with Saudi Vision 2030 and global sustainability goals, advocating for the revival and integration of these motifs into modern urban design to ensure the continued appreciation and recognition of Makkan architectural heritage. Full article

A comprehensive X-ray topography analysis of two selected aluminum nitride (AlN) bulk crystals is presented. We compare surface inspection X-ray topography in back-reflection geometry with high-energy transmission topography in the Lang and Laue configuration using the monochromatic K_α1 excitation wavelength of copper, silver, and tungsten, respectively. A detailed comparison of the results allows the assessment of both the high- and low-energy X-ray topography methods with respect to performance and structural information, giving essential feedback for crystal growth. This is demonstrated for two selected AlN freestanding faceted crystals up to 8 mm in thickness grown in all directions using the physical vapor transport (PVT) method. Structural defects of all facets of the crystals are determined using the X-ray topography in back-reflection geometry. The mean threading dislocation densities are 480 ± 30 cm⁻² for both crystals of either the Al- or N-face. Clustering of dislocations could be observed. The m-facets show the presence of basal plane dislocations and their accumulation as clusters. The integral transmission topographs of the $10\overline{1}0$ (m-plane) reflection family show that basal plane dislocations of the screw type in ${\displaystyle \frac{1}{3}}⟨\overline{1}2\overline{1}0⟩$ directions decorate threading dislocation clusters. Three-dimensional section transmission topography reveals that the basal plane dislocation clusters mainly originate at the seed boundary and propagate in the ${\displaystyle \frac{1}{3}}⟨\overline{1}2\overline{1}0⟩$ direction along the growth front. In newly laterally grown material, the Borrmann effect has been observed for the first time in PVT-grown bulk AlN, indicating very high structural perfection of the crystalline material in this region. This agrees with a low mean FWHM of 10.6 arcsec of the $10\overline{1}0$ reflection determined through focused high-energy Laue transmission mappings. The latter method also opens the analysis of the $∆2\theta$-shift correlated to the residual stress distribution inside the bulk crystal, which is dominated by dislocation clusters. Contrary to Lang transmission topography, the de-focused high-energy Laue transmission penetrates the 8 mm-thick crystal enabling a defect analysis in the bulk. Full article

Catalytic hydrogenolysis of lignin to produce high-value monophenols has emerged as a pivotal strategy in modern biorefineries. In this study, we synthesized spherical nitrogen-doped porous carbon (SNCB) materials by using Al/Co-BTC as a precursor, introducing melamine as a supplementary carbon and nitrogen source, and activating the material with NaOH solution. The SNCB framework was decorated with Cu-Pd bimetallic nanoparticles, exhibiting outstanding catalytic activity in the hydrogenolytic depolymerization of organosolv lignin. The Cu-Pd@SNCB catalyst exhibited remarkable activity, attributed to the hierarchical porous structure of SNCB that facilitated metal nanoparticle dispersion and reactant accessibility. The synergistic effect between Cu as the reactive site for reactant adsorption and Pd as the reactive site for H₂ adsorption enhanced the catalytic activity of the catalyst. Systematically optimized conditions (2 MPa H₂, 270 °C, 3 h) yielded 43.02 wt% phenolic monomers, with 4-(3-hydroxypropyl)-2,6-dimethoxyphenol dominating the product profile at 46.3% selectivity. The catalyst and its reaction products were analyzed using advanced characterization techniques, including XPS, XRD, TEM, SEM, BET, GC-MS, GPC, 2D HSQC NMR, and FT-IR, to elucidate the reaction mechanism. The mechanism proceeds through: (1) nucleophilic substitution of the β-O-4 hydroxyl group by MeOH, followed by (2) simultaneous hydrogenolytic cleavage of C_β-O and C_α-O bonds mediated by Cu-Pd@SNCB under H₂ atmosphere, which selectively produces 4-(3-hydroxypropyl)-2,6-dimethoxyphenol and 4-propyl-2,6-dimethoxyphenol. This study proposes a bimetallic synergistic mechanism, offering a general blueprint for developing selective lignin valorization catalysts. Full article

Considering the importance of organic functionalization of MOFs, we here report a simple, tunable and efficient one-step post-modification procedure for introducing amino and carboxylic groups into the mesoporous metal–organic framework Al- and Cr-MIL-101-NH₂ based on its reaction with alkyl bromides. This procedure allows also access to polyfunctionalized MIL-101 decorated with both carboxylic and primary amino groups. Other chemical functions, such as alcohols and alkynes, were also successfully introduced by this method. Full article

TiN thin films are widely used as protective and decorative coatings for tools in industry. Previous studies have focused on the deposition of TiN coatings on substrates by reactive magnetron sputtering, whereas the use of TiN targets avoids problems such as ‘nitrogen contamination’ and ‘target poisoning’. TiN coatings were grown on silicon wafers and cemented carbide substrates by varying the parameters of the magnetron sputtering plasma source, operating Ar pressure and deposition temperature. The experimental results show the better mechanical properties of ceramic materials deposited using radio frequency (RF) magnetron sputtering. During RF magnetron sputtering, the hardness of the coating increased significantly to 17 Gpa when the deposition working pressure was reduced from 1.5 Pa to 0.5 Pa. The coefficient of friction tends to decrease as the deposition temperature increases, and at 400 °C the coefficient of friction between the deposited film and the friction pair made of Al₂O₃ material is only 0.36. The nano-scratch experimental tests concluded that the TiN coatings deposited at 300 °C conditions had the best adhesion to the substrate at an Ar pressure of 0.5 Pa under an RF source. Full article

The stable adsorption configurations, electronic structures, and dissociation properties of 2-chlorophenol on pristine and Al-decorated ZnO monolayer are investigated using density functional theory (DFT). Our results indicate that the interaction between 2-chlorophenol and pristine ZnO monolayer is weak, while Al-modified ZnO monolayer can significantly enhance the adsorption of 2-chlorophenol. Therefore, compared to the pristine ZnO monolayer, the ZnO monolayer modified with Al is more sensitive to 2-chlorophenol molecules. Moreover, both pristine ZnO and Al decorated ZnO monolayers exhibit lower barriers for the dissociation of 2-chlorophenol molecules. These results provide a deeper understanding of the adsorption and dissociation performance of the ZnO monolayer for 2-chlorophenol molecules, which will contribute to the further application of ZnO in the fields of catalysts and gas sensing. Full article

In this article, I aim to address one of the most characteristic decorative elements of the Almohad period, the so-called sebka decoration. With this aim in mind and through the research carried out and the examples that have been preserved, I consider it appropriate to know the origin of this ornamental motif that is so recurrent in the Andalusian architectural panorama and to analyse not only its compositional scheme but also the different formal variants that arose around it. Furthermore, its use in other buildings in the Kingdom of Castile is a further indication that allows us to approach a scenario where cultural and artistic transfer between al-Andalus and the Christian territories was a reality. Full article

Metal–oxide interfaces play a prominent role in heterogeneous catalysis. Tailoring the metal–oxide interfaces effectively enhance the catalytic activities and thermal stability of noble metal catalysts. In this work, polyvinyl alcohol-protected reduction and L-arginine induction methods are adopted to prepare Pd catalysts (Pd/Al₂O₃-xCeO₂) that are selectively decorated by CeO₂, which form core–shell-like structures and generate more Pd-CeO₂ interfacial sites, so that the three-way catalytic activity of Pd/Al₂O₃-xCeO₂ catalysts is obviously significantly enhanced due to more adsorption oxygen at the interface of Pd-CeO₂ and good low-temperature reducibility. At the moment, the Pd/Al₂O₃-xCeO₂ catalysts exhibit excellent thermal stability after being calcined at 900 °C for 5 h, owing to the Pd species being highly redispersed on CeO₂ and part of the Pd species being incorporated into the lattice of CeO₂. This is a major reason for the Pd/Al₂O₃-xCeO₂ catalysts to maintain high catalytic activity after aging at high temperatures. It is concluded that the metal–oxide interfaces and the interaction between Pd NPs and CeO₂ are responsible for the excellent catalytic performance and stability of Pd/Al₂O₃-xCeO₂ catalysts in three-way reactions. Full article

Palladium phthalocyanine (PdPc) and palladium phthalocyanine integrated with tin–zinc oxide (PdPc:SnZnO) were prepared using a simple chemical approach, and their structural and morphological properties were identified using X-ray diffraction, energy dispersive X-ray analysis, scanning electron microscopy, and transmission electron microscopy techniques. The PdPc:SnZnO nanohybrid revealed a polycrystalline structure combining n-type metal oxide SnZnO nanoparticles with p-type organic PdPc molecules. The surface morphology exhibited wrinkled nanofibers decorated with tiny spheres and had a large aspect ratio. The thin film revealed significant optical absorption within the ultraviolet and visible spectra, with narrow band gaps measured at 1.52 eV and 2.60 eV. The electronic characteristics of Al/n-Si/PdPc/Ag and Al/n-Si/PdPc:SnZnO/Ag Schottky diodes were investigated using the current–voltage dependence in both the dark conditions and under illumination. The photodiodes displayed non-ideal behavior with an ideality factor greater than unity. The hybrid diode showed considerably high rectification ratio of 899, quite a low potential barrier, substantial specific photodetectivity, and high enough quantum efficiency, found to be influenced by dopant atoms and the unique topological architecture of the nanohybrid. The capacitance/conductance–voltage dependence measurements revealed the influence of alternative current signals on trapped centers at the interface state, leading to an increase in charge carrier density. Full article

Under benign conditions, bone tissue can regenerate itself without external intervention. However, this regenerative capacity can be compromised by various factors, most importantly related with the extent of the injury. Critical-sized defects, exceeding the body’s natural healing ability, demand the use of temporary or permanent devices like artificial joints or bone substitutes. While titanium is a widely used material for bone replacement, its integration into the body remains limited. This often leads to the progressive loosening of the implant and the need for revision surgeries, which are technically challenging, are commonly associated with high complication rates, and impose a significant economic burden. To enhance implant osseointegration, numerous studies have focused on the development of surface functionalization techniques to improve the response of the body to the implant. Yet, the challenge of achieving reliable and long-lasting prostheses persists. In this work, we address this challenge by applying a robust and versatile biofunctionalization process followed by the decoration of the material with oligopeptides. We immobilize four different peptides (RGD, CS-1, IKVAV, PHSRN) on R-THAB^® functionalized surfaces and find them to be highly stable in the long term. We also find that RGD is the best-performing peptide in in vitro cell cultures, enhancing adhesion, proliferation, and osteogenic differentiation of mesenchymal stem cells. To assess the in vivo effect of RGD-decorated Ti-6Al-4V implants, we develop a calvarial model in murine hosts. We find that the RGD-decoration remains stable for 1 week after the surgical procedure and reduces post-implantation macrophage-related inflammation. These results highlight the potential of peptide decoration on R-THAB^® functionalized surfaces to expedite the development of novel metallic biomaterials with enhanced biocompatibility properties, thereby advancing the field of regenerative medicine. Full article

With the developments in nanotechnology, the elaborate regulation of microstructure shows attractive potential in the design of new composite materials. Herein, composite materials composed of graphene network filled with metal nanoparticles are analyzed to optimize the fabrication process and mechanical properties. In the present work, molecular dynamic simulations are used to analyze the possibility of obtaining a composite structure with Ni-decorated graphene. The weak bonding at the graphene–copper and graphene–aluminum interfaces is manipulated by functionalizing graphene with nickel nanoclusters. It is found that Ni decoration considerably increases interfacial bonding and, at the same time, prevents the formation of a strong graphene network. It is found that Ni decoration for the Al/graphene composite increases the its ductility by 0.6, while increasing it for the Cu/graphene composite by about 0.5. Ultimate tensile strength of the composite with Al and Cu is close and equal to 22 GPa, respectively. The strength of the composite with Ni-decorated graphene is much lower and equal to 13 GPa for Cu/graphene/Ni and 17 GPa for Al/graphene/Ni. While Young’s modulus for the Cu/graphene composite is 18 GPA, for Al/graphene, Al/graphene/Ni, and Cu/graphene/Ni, it is 12 GPa. The obtained results demonstrate the future prospects of the graphene modification for better composite enhancement. Full article

This paper addresses a critical gap in the study of Islamic architecture by exploring the interconnected relationship between Arabic calligraphy and architectural design. Specifically, it examines the principles guiding the placement of Islamic calligraphy within the interior and exterior spaces of Islamic public buildings through a qualitative analysis of two notable case studies, the Al-Hambra Palace in Granada, Spain, and the Al-Azem Palace in Hama, Syria. This research elucidates fundamental principles that underpin the integration of calligraphy in Islamic architectural contexts. To enhance the robustness of the findings, interviews were conducted with three expert master calligraphers, providing skillful insights that enrich the understanding of calligraphy placement. This study reveals significant implications for the decoration of walls and ceilings in Islamic buildings. However, the findings are limited by the scope of the case studies and the subjective interpretations of the interviewed experts. This research contributes valuable knowledge to the field, informing contemporary architectural practices and the preservation of cultural heritage. Full article

In this study, we successfully employed the plasma electrolytic oxidation (PEO) technique to create a uniform white ceramic layer on the surface of the 6061 aluminum alloy using K₂ZrF₆ and Na₂WO₄ as colorants. A scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) and X-ray diffraction (XRD) were used to characterize the coatings, and we used an electrochemical workstation to test their corrosion protection properties. The corrosion resistance of the coatings was analyzed using potentiodynamic polarization curves. The results showed that K₂ZrF₆ addition whitened the coating with ZrO₂ as the main phase composition, inhibiting Al substrate depletion and enhancing coating corrosion resistance. A small amount of Na₂WO₄ decreased the coating’s L* value, successfully constructing ceramic coatings with L* (coating brightness) values ranging from 70 to 86, offering broad application prospects for decorative coatings. Full article