Search Results (1,458)

This research aims to investigate the modifications of the structural, dielectric, and sensing properties of CaFeO_3−δ ceramics produced by solid-state reaction induced by varying sintering temperatures in the range of 1000–1200 °C. A single crystallographic orthorhombic (Pcmn) structure was revealed by X-ray diffraction with Rietveld analysis, both for the powders and sintered ceramics, irrespective of the sintering temperature. The increase in the sintering temperature induces better densification and a larger grain size. Dielectric measurements reveal a pronounced enhancement of the relative permittivity, reaching 2 × 10⁵ at 1 kHz and 330 °C for the sample sintered at 1200 °C/4 h. This composition also displays the highest electrical conductivity, 0.4 S/m at 1 MHz. Cole–Cole analysis indicates a clear deviation from ideal Debye behavior, while the relaxational features of the dielectric permittivity suggest a strong correlation between the dielectric response and Fe-related conduction mechanisms. Gas sensing tests show that the ferrite ceramics exhibit consistent ethanol response trends. The ceramic sintered at 1200 °C/4 h achieved the highest sensitivity, of 56.28%, which can be attributed to its higher density, larger ceramic grains, and reduced low-frequency conductivity. The CaFeO_3−δ ceramic sintered at 1200 °C/4 h shows a combination of high permittivity, enhanced conductivity, and strong ethanol sensitivity, making it a promising material for dielectric components, capacitive devices, and gas sensing applications. Full article

While many [FeFe]-hydrogenase biomimetics are effective proton-reduction catalysts, few are active for H₂ oxidation, and examples containing both a pendant amine group, able to act as a proton relay, and a second redox center, both essential features of the enzymes, are rare. Here we report the preparation and oxidation chemistry of two ferrocene-functionalized amino-diphosphines (PCNCP), (CH₂PR₂)₂NCH₂Fc (R = Ph (1), Cy (2)), and their ethylenedithiolate (edt) diiron complexes, [Fe₂(CO)₄(μ-edt){κ²-(R₂PCH₂)₂NCH₂Fc}] (R = Ph (3), Cy (4)). Their crystallographic characterization shows that PCNCP occupies an apical–basal position. CV responses are slightly R-dependent, showing for 3 and 4 in three separate oxidative processes assigned to successive one-electron oxidation of the diiron core (quasireversible), appended Fc (reversible), and the amine–diiron moiety (irreversible), as confirmed by IR and UV–Vis spectroelectrochemical studies supported by Density Functional Theory (DFT) and Time-dependent Density Functional Theory (TDDFT) calculations. The first oxidation results in a structural rearrangement of the Fe(PNP)(CO) unit and the formation of a semi-bridging carbonyl. Slow protonation of 3 with HBF₄∙Et₂O affords the corresponding N-protonated cation in acetone, whilst μ-hydride products dominate for both 3 and 4 in CD₂Cl₂. A preliminary H₂ oxidation study was carried out with 3, and while there was some evidence of activity, it was much lower than reported for alkyl-functionalized PCNPC diiron derivatives. Full article

Laser powder bed fusion (LPBF) of AA7075 is severely constrained by a narrow process window and susceptibility to defect formation (hot cracking and porosity), which often dominates performance. In this study, 5 wt.% AlCoCrFeNi_2.1 high-entropy alloy (HEA) particles, volumetric energy density (VED = 74–222 J·mm⁻³), and subsequent T6 heat treatment were systematically investigated to reveal their combined effects on defect structure, crystallographic texture/substructure, and tensile behaviour. Quantitative EBSD shows a measurable grain refinement in the as-built state (average grain size 13.44 → 11.80 µm, ~12%) accompanied by a pronounced weakening of the <001> fibre texture (maximum MRD 4.94 → 2.38), indicating disrupted epitaxial growth and a more dispersed orientation distribution. After T6, the reinforced alloy retains a higher low-angle boundary fraction (31.62% vs. 24.17% in unreinforced AA7075) and a higher kernel average misorientation (0.80° vs. 0.60°), consistent with particle-stabilised substructure retention and retarded recovery. Across all VEDs, AA7075-HEA exhibits higher microhardness (compared with AA7075, the addition of HEA increases the hardness by roughly 20–50 HV) and tensile strength, with the intermediate VED (140.74 J·mm⁻³, T6 states) yielding the best performance. While macroscopic cracking is not fully eliminated, the results clarify that HEA-enabled texture/substructure modifications can contribute to enhanced defect tolerance and are more effectively translated into tensile performance when the as-built defect severity is controlled. These findings provide quantitative insights into defect–microstructure–property coupling in LPBF AA7075-HEA composites from as-built to T6 states. Full article

High-Al-content AlGaN microrods represent an effective platform for engineering deep-ultraviolet (DUV) emission. Here, we fabricated AlGaN microrods with varying diameters (2, 3, and 4 μm) via a top-down approach involving inductively coupled plasma dry etching followed by a KOH wet chemical modification. Their crystallographic facets and size-dependent optical properties were systematically investigated using scanning electron microscopy (SEM), cathodoluminescence (CL) spectroscopy, and CL mapping. We found that the KOH treatment selectively forms a-plane-dominated sidewalls on the high-Al-content portion of the microrods, whereas the etch pit bottoms stabilize as m-plane facets. Notably, the CL spectra show that the band-edge emission intensity of the 2 μm microrods is enhanced by a factor of 3.76 compared to the 4 μm structures. CL mapping further unveils the competitive dynamics between radiative recombination within the quantum wells and non-radiative recombination at surface states. These findings pinpoint 2 μm as the optimal diameter among the investigated range for maximizing spontaneous emission from these high-Al-content AlGaN microrods. Full article

For structural metallic materials, performance enhancement has traditionally relied on complex adjustments of chemical composition and heat treatment processes. However, these approaches are complex, costly, and lack sustainability. Metal additive manufacturing (AM) has unique cooling characteristics, providing it with a distinctive approach. In this study, laser powder bed fusion (LPBF) technology was used to prepare high-performance 1080 carbon steel. The study selected three groups of process parameters (VED = 92.59 J/mm³) with high density (relative density > 98%) and achieved excellent mechanical properties: the ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) reach 1745.4 MPa, 1455.13 MPa, and 6.77% respectively. The effects of process parameters on microstructure and mechanical properties were investigated. It is found all specimens exhibited a characteristic martensitic needle-like grain morphology without significant crystallographic texture. The microstructure displayed substantial changes as VED varied, with martensite content progressively decreasing with increasing VED. Correspondingly, as the VED increases from 92.59 J/mm³ to 225.69 J/mm³, the UTS, YS, and EL decrease by 39.0%, 36.1%, and 3.4%, respectively. This work demonstrates the feasibility of achieving high-performance metallic components by precisely controlling additive manufacturing process parameters to manipulate the microstructure of simple alloys, thereby eliminating the need for complex alloying or post-processing heat treatments. Full article

The superconducting transition temperature of ${\mathrm{CaC}}_6$ is investigated within the Roeser–Huber (RH) formalism using both rhombohedral and hexagonal crystallographic representations. While these two descriptions are crystallographically equivalent, they differ in their geometric construction of superconducting paths and near-atom environments. In the rhombohedral representation, only translationally closed Ca–Ca vectors consistent with the primitive lattice are considered, yielding three symmetry-distinct RH paths. In the hexagonal representation, the same superconducting channels are expressed in an expanded conventional cell, where some paths appear as unfolded or symmetry-related sublattice connections. For each representation, the RH path lengths and effective near-atom counts are evaluated and used to compute the superconducting transition temperature. The rhombohedral description yields $T_c^{\left(\mathrm{calc}\right)}=10.4$ K, while the hexagonal representation gives $T_c^{\left(\mathrm{calc}\right)}=10.9$ K, both in good agreement with the experimental value $T_c^{\left(\exp \right)}=11.5$ K. The difference between the calculated values amounts to approximately 5%. These results show that the underlying RH superconducting channels and their near-atom environments are representation independent, while minor quantitative differences in $T_c^{\left(\mathrm{calc}\right)}$ arise from metric redistribution of equivalent paths. This directly confirms that the RH formalism captures intrinsic structural features of superconductivity rather than artifacts of unit-cell representation. Full article

Reproductive management in goats remains challenging due to seasonal breeding and the use of hormones that raise concerns about immunogenicity, cost, sustainability, and animal welfare. In this study, we evaluated date palm pollen (Phoenix dactylifera L.) (DPP) as a natural source of estrogenic compounds capable of modulating reproductive function. DPP was extracted using methanol, ethanol, acetone, and hexane, and the extracts were analyzed by ultra-performance liquid chromatography. Quercetin and coumestrol were detected in the methanolic and ethanolic extracts at comparable levels (quercetin 0.043–0.044 mg/g; coumestrol 0.987–1.015 mg/g of extract) (p > 0.05). The acetone extract contained significantly lower concentrations (quercetin 0.017 mg/g; coumestrol 0.033 mg/g of extract), while the hexane extract showed no detectable amounts. Molecular docking using the crystallographic structure of estrogen receptor alpha (PDB:6PIT) showed that both compounds interact with key residues of the receptor’s ligand-binding domain. Coumestrol exhibited the highest affinity (−9.3 kcal/mol), surpassing 17-β estradiol (−8.9 kcal/mol), forming several hydrogen bonds and hydrophobic contacts. Quercetin showed a lower affinity (−7.2 kcal/mol) but maintained stabilizing interactions compatible with partial agonist activity. Overall, methanol and ethanol were the most effective solvents for extracting phytoestrogens from DPP, and the findings support their potential as natural alternatives to hormones for estrus induction in goats. Full article

This study investigates the rational design of a dinuclear zinc(II) coordination polymer, (C₃₆H₃₄Br₂N₈O₄S₂Zn₂), to explore how halogen substitution and ligand choice modulate structural architecture, contributing to the development of functional coordination polymers with tailored properties. The complex was synthesized from a bromo-substituted semicarbazone Schiff base ligand (L1) and a rigid bipyridine linker (L2) under solvothermal conditions, and its structure was elucidated using single-crystal X-ray diffraction (SCXRD), complemented by characterization via powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. Crystallographic analysis reveals that the complex crystallizes in the triclinic space group P-1, forming discrete dinuclear units where each Zn(II) center adopts a distorted square–pyramidal geometry; these units are extended into one-dimensional chains by bridging L2 ligands and further assembled into a three-dimensional supramolecular network through hydrogen-bonding interactions. PXRD confirms the high phase purity of the bulk material, TGA indicates notable thermal stability up to 130 °C, and IR spectroscopy validates the coordination modes and hydrogen-bonding network. This work elucidates the critical role of the bromo substituent and rigid ancillary ligands in modulating the solid-state structure of the zinc(II) complex. The revealed structure-directing principles provide a valuable reference for the rational design of functional coordination polymers. Full article

Chronic, dysregulated inflammation contributes to colitis-associated colorectal cancer (CRC), and the cGAS–STING pathway represents a central but therapeutically challenging node because both insufficient and excessive STING activity can be pathogenic. Here, we integrate AlphaFold3 (AF3) receptor modeling, diffusion-based docking, and explicit-solvent molecular dynamics (MD) simulations to characterize how the marine briarane diterpenoid excavatolide B (ExcB) engages the human STING (hSTING) cyclic dinucleotide (CDN)-binding cleft. The structural integrity of the AF3 hSTING model was validated through both intrinsic confidence scores (pLDDT, PAE) and comparative benchmarking against experimental CTD structures (PDB: 4EF5, 6A05). Notably, the local geometries of key pocket-defining residues—including His157, Tyr167, and Thr263—remained consistent with established crystallographic data. Across three independent 100 ns MD replicas, ExcB exhibits a consistent spatial progression from an entrance-proximal pose at the solvent-accessible rim of the cleft (Site-2) to a more embedded, non-canonical corridor on the Cys148-adjacent side (Site-2′). Distance and contact analyses support a predominantly non-covalent within-cleft mechanism and do not indicate a persistent approach to the literature-reported covalent regime near Cys91. Residue-level profiling over the stabilized sampling window defines a reproducible corridor “contact signature” and reveals within-cavity sub-pose diversity rather than a single rigid bound pose. Mechanistically, competitive docking of the native agonist cGAMP to ExcB-conditioned receptor snapshots yields consistently less favorable docking outcomes in ExcB-conditioned conformations than docking to the native/open receptor; retaining ExcB coordinates does not further penalize cGAMP, supporting a receptor-reshaping (conformational conditioning) component rather than persistent static steric clash. Our findings characterize ExcB as a non-covalent modulator targeting a cryptic pocket within the STING CDN-binding cleft, establishing a structural basis for targeted mutagenesis and structure-activity relationship (SAR) studies. Full article

Molybdenum disulfide (MoS₂) films are promising solid lubricants for aerospace and other advanced applications, yet their tribological performance is highly sensitive to environmental conditions. To enhance environmental adaptability, Zr-doped MoS₂ composite films were prepared by magnetron co-sputtering, and their composition, microstructure, mechanical properties, and tribological behavior were systematically investigated. The results showed that the as-deposited MoS₂ films exhibited a nearly stoichiometric sulfur-to-molybdenum ratio (S/Mo ≈ 2), while the Zr-doped MoS₂ composite films showed sulfur-deficient, sub-stoichiometric ratios (S/Mo < 2). Pure MoS₂ films displayed a porous columnar structure, whereas with the incorporation of Zr, the columnar structure becomes progressively more compact. Moreover, the film structure transitions from a purely crystalline form to a two-phase structure with both crystalline and amorphous phases coexisting. The hardness and elastic modulus of the films increased with the addition of Zr, mainly due to the densification of the structure and the disorder introduced in the film. Moderate Zr doping markedly improved the friction and wear performance of composite films across vacuum, atmospheric, and humid environments. The optimal film achieved a coefficient of friction (COF) of 0.02 and wear rate of 6.23 × 10⁻⁸ mm³/N·m in vacuum and COFs of 0.10 with low wear rates in both atmospheric and humid conditions. By adjusting the Zr target power to modulate Zr content, the crystallographic orientation and microstructure of MoS₂-Zr composite films could be tailored, thereby regulating their mechanical and tribological properties. This study provides theoretical guidance for the application of metal-doped MoS₂ composite films under alternating environmental conditions. Full article

Structural symmetry is increasingly explored as a design concept in advanced materials for wastewater treatment, though its definition and practical relevance remain unclear. This review provides a critical overview of how symmetry (including crystallographic, pore-network, active-site, and architectural symmetry) affects pollutant removal. Representative material systems such as adsorbents, catalysts, and mixed-matrix membranes are examined for the removal of typical pollutants, including dyes, heavy metals, pharmaceuticals, and emerging contaminants. Symmetry is linked to improved transport uniformity, enhanced charge-carrier migration, facet-dependent reactivity in catalysts, and increased stability during cyclic operation. Symmetric architectures are compared with asymmetric and defect-rich designs, highlighting cases where asymmetry outperforms, particularly in complex matrices dominated by surface chemistry or kinetic accessibility. Performance metrics are discussed in their experimental contexts, with emphasis on qualitative structure–performance relationships. Environmental and economic implications are addressed qualitatively, focusing on life-cycle considerations, cost trends, scalability, and industrial feasibility rather than comprehensive techno-economic analyses. This review highlights when symmetry is beneficial, when its influence is limited, and how combining symmetry with asymmetry or defect engineering can lead to more practical wastewater treatment solutions. Full article

This study focused on investigating the influence of zinc on tin pest, both alone and in combination with lead and copper. Based on the known composition of the organ pipe from Trpín, five model alloys were prepared, from which model samples were produced. The model alloys were exposed to low temperatures for 100 days or until complete degradation occurred. The kinetics of the transformation were compared for annealed and non-annealed samples. It was confirmed that the transformation is much faster in samples with retained internal stress. A comparison of the Avrami coefficients indicated similar nucleation behavior for both sample types. Phase transformation was observed in samples containing tin, copper, zinc, and lead, as well as those containing only copper and lead. This suggests that even a relatively small amount of zinc (0.25 wt.%) and copper (0.9 wt.%) can affect the course of tin pest in an alloy containing 13 wt.% lead. Transformation progressed more slowly in samples with only 0.25 wt.% zinc than in pure tin, likely due to the limited solubility of zinc in a tin with low concentrations of alloying elements. The crystallographic structure of both the model alloys and the original historical pipe material was studied using transmission electron microscopy (TEM). In almost all model samples, zinc was uniformly dissolved in the tin matrix. However, in the original pipe, zinc was primarily located at grain boundaries and in association with copper. This indicates that zinc was not intentionally added to the historical alloy but likely appeared in the alloy as a contaminant of impure copper. Full article

Magnetic Barkhausen noise (MBN) analysis has recently emerged as a powerful nondestructive tool for probing crystallographic orientation, phase transformation, and microstructural stress distribution in ferromagnetic materials. This review aims to summarize recent advances in understanding the relationship between crystallographic texture, dislocation density, and magnetic domain dynamics across different classes of steels and surface coatings. Emphasis is placed on the influence of crystal structure symmetry, residual stress gradients, and coating–substrate interactions on the MBN response. The article also discusses recent modeling approaches and potential integration of MBN with complementary techniques such as EBSD and XRD for microstructural diagnostics and materials design. Full article

Ag-Sn-S/Se semiconductors, particularly Ag₈SnS₆ and Ag₈SnSe₆, have emerged as promising thermoelectric (TE) materials due to their intrinsically low lattice thermal conductivity and favorable electronic transport properties. Owing to their direct and super-narrow bandgaps, these semiconductors also hold significant potential for photovoltaic (PV) applications, especially in near-infrared (NIR) energy harvesting and tandem architecture. This review provides a detailed analysis of the synthesis strategies, crystallographic evolution, phase transition mechanisms, and bandgap modulation in Ag-Sn-S/Se semiconductors. Particular focus is given to the structural adaptability of argyrodite-type compounds, where intrinsic cationic disorder and halogen-assisted anion substitution collectively enable the fine-tuning of electronic transport and lattice dynamics. TE performance is evaluated in terms of carrier mobility and thermal conductivity, highlighting a significant improvement in figure of merit. The review further explores the potential of Ag-Sn-S/Se semiconductors in energy conversion PVs, particularly as photoabsorber layers and counter electrode materials. Despite initial demonstrations, systematic studies on device integration remain limited, highlighting substantial opportunities for future research aimed at optimizing their optoelectronic interfaces and overall PV performance. This review ultimately discusses the potential of Ag-Sn-S/Se semiconductors, emphasizing their tunable properties as being key to next-generation PV and thermoelectric technologies. It highlights the current achievements and unresolved challenges, outlining strategic pathways for future research and device integration. Full article

Existing macroscopic finite element models for electron beam welding (EBW) typically assume isotropic material behavior, often failing to accurately predict residual stresses induced by strong crystallographic textures. To address this limitation, this study established a sequential dual-scale coupled numerical model bridging micro-texture to macro-mechanics by combining the crystal plasticity finite element method (CPFEM) with thermal-elastic-plastic theory. Representative volume elements (RVEs) incorporating α and β dual-phase characteristics were constructed based on electron backscatter diffraction (EBSD) data from the TA15 weld cross-section. Through simulated tensile and shear calculations on the RVEs, homogenized orthotropic stiffness matrices and Hill yield constitutive parameters were derived and mapped onto the macroscopic model. Simulation results indicate that the proposed model maintains the prediction error for molten pool morphology within 16.3%, while effectively correcting the stress overestimation inherent in isotropic models. Specifically, it adjusts the peak longitudinal residual stress at the weld center from 800 MPa to approximately 350 MPa, significantly reducing the anomalous “M-shaped” stress distribution. By successfully capturing shear stress components, this work provides a high-fidelity computational approach for predicting complex stress states in welded joints, offering critical insights for structural integrity assessment. Full article