Search Results (776)

Free gasses of spinless fermions moving on a lattice-symmetric geometric background are considered. Their topological properties at zero temperature can be used to classify their Fermi seas and associated boundaries. The flat orbifolds ${\mathbb{R}}^d/\mathrm{\Gamma }$, where $\mathrm{\Gamma }$ is the crystallographic group of symmetry in d-dimensional momentum space, are used to accomplish this task. Two topological classes exist for $d=1$: an interval, which is identified as a conductor, and a circumference, which corresponds to an insulator. The number of topological classes increases to 17 for $d=2$: 8 have the topology of a disk, that are generally recognized as conductors, and 4 correspond to a two-sphere, matching insulators. Both sets eventually contain a finite number of conical singularities and reflection corners at the boundaries. The remaining cases in the listing relate to conductors (annulus, Möbius strip) and insulators (two-torus, real projective plane, Klein bottle). Examples that fall under this list are given, along with physical interpretations of the singularities. It is anticipated that the findings of this classification will be robust under perturbative interactions due to its topological character. Full article

Two series of tri(2-furyl)- and triphenylphosphine-gold(I) complexes, with pyridyl- and pyrimidine-thiolate ligands containing electron-donating (-CH₃) and electron-withdrawing (-CF₃) substituents were synthesized and investigated for cell viability inhibitions. Prior results indicate that several of the gold(I) complexes in these series have high antifungal properties. The observed link between antifungal and anticancer activity provided motivation to investigate their antiproliferative effects, reported here. The synthesized compounds from both series were characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy, mass spectrometry (MS), infrared and UV-Vis spectroscopy, and solution stability studies. In addition, an X-ray crystallographic study was conducted on one of the gold(I) complexes. Analyte solubilities in McCoy’s 5A cell media were evaluated by ICP-MS. Initial screening studies were conducted on the two series to evaluate cell viability using the SK-BR-3 cell line. All ten gold(I) complexes exhibited sub-µM cytotoxicity and the most potent representatives, one from each series, were selected for further evaluation in four additional cell lines. Half-maximal effective concentrations (EC₅₀) were determined for the MCF7 and MDA-MB-231 malignant mammary cell lines as well as the two control cell lines, HEK293T and MCF10A, to probe for specificity. Results indicate significant selectivity towards inhibition of cancer cells compared to non-transformed for tri(2-furyl)- and triphenylphosphine-gold(I) complexes with the 3,5-dimethylpyrimidine thiolate ligand when dissolved in cell media. Additional studies including 1% DMSO as a solubilizing agent revealed its significant impact on cellular responses. Full article

Tin selenide (SnSe) is a sustainable, lead-free IV–VI semiconductor whose layered orthorhombic crystal structure induces pronounced electronic and phononic anisotropy, enabling diverse energy-related functionalities. This review systematically summarizes recent progress in understanding the structure–property–processing relationships that govern SnSe performance in thermoelectric and optoelectronic applications. Key crystallographic characteristics are first discussed, including the temperature-driven Pnma–Cmcm phase transition, anisotropic band and valley structures, and phonon transport mechanisms that lead to intrinsically low lattice thermal conductivity below 0.5 W m⁻¹ K⁻¹ and tunable carrier transport. Subsequently, major synthesis strategies are critically compared, spanning Bridgman and vertical-gradient single-crystal growth, spark plasma sintering and hot pressing of polycrystals, as well as vapor- and solution-based thin-film fabrication, with emphasis on process windows, stoichiometry control, defect chemistry, and microstructure engineering. For thermoelectric applications, directional and temperature-dependent transport behaviors are analyzed, highlighting record thermoelectric performance in single-crystal SnSe at hi. We analyze directional and temperature-dependent transport, highlighting record thermoelectric figure of merit values exceeding 2.6 along the b-axis in single-crystal SnSe at ~900 K, as well as recent progress in polycrystalline and thin-film systems through alkali/coinage-metal doping (Ag, Na, Cu), isovalent and heterovalent substitution (Zn, S), and hierarchical microstructural design. For optoelectronic applications, optical properties, carrier dynamics, and photoresponse characteristics are summarized, underscoring high absorption coefficients exceeding 10⁴ cm⁻¹ and bandgap tunability across the visible to near-infrared range, together with interface engineering strategies for thin-film photovoltaics and broadband photodetectors. Emerging applications beyond energy conversion, including phase-change memory and electrochemical energy storage, are also reviewed. Finally, key challenges related to selenium volatility, performance reproducibility, long-term stability, and scalable manufacturing are identified. Overall, this review provides a process-oriented and application-driven framework to guide the rational design, synthesis optimization, and device integration of SnSe-based materials. Full article

The ability to precisely control the electronic bandgap is crucial for tailoring two-dimensional (2D) materials for optoelectronic applications. In this work, we systematically investigate the electronic structure of 2D tin monoxide (SnO) across various layer thicknesses (monolayer to tetralayer) and crystallographic symmetries using first-principles calculations. Our results reveal a strong dependence of the bandgap on the number of layers, which decreases dramatically from 3.94 eV in the monolayer to nearly metallic in the tetralayer. Furthermore, different space group symmetries are found to significantly influence the bandgap, providing an additional degree of freedom for property tuning. This bandgap engineering is quantitatively linked to enhanced interlayer electronic coupling, as evidenced by a progressive increase in interlayer charge transfer with layer count. Our findings establish a clear structure–property relationship and offer practical guidance for designing SnO-based devices in flexible electronics and tunable optoelectronics. Full article

This study investigates phase formation in the Sr–Zn–Eu³⁺ orthophosphate system, focusing on double- and triple-phosphates. The isomorphisms and phase formation in Sr_3–1.5xEu_1+x(PO₄)₃, Sr_9–1.5xZn_1.5Eu_x(PO₄)₇, Sr_9.5–1.5xZnEu_x(PO₄)₇, Sr_3–xZn_xEu(PO₄)₃, and Sr_3–xZn_x(PO₄)₂ series were studied using powder X-ray diffraction and Rietveld refinement. A ternary phase diagram was constructed, identifying concentration limits for pure phases and multi-phase regions as well as areas of stabilization of strontiowhitlockite-, palmierite-, eulytite-, and strontiohurlbutite-type phases. The combinatorial complexity of Sr-based phosphates is discussed. The β-Sr₃(PO₄)₂ isostructural to whitlockite was found to exhibit the highest isomorphic capacity for Eu³⁺ cations, which is advantageous for its application as a red-emitting phosphor. Photoluminescence properties were studied, and analyzed based on structural data. Photoluminescence studies confirmed intense red-emission dominated by the ⁵D₀ → ⁷F₂ transition of Eu³⁺, with the β-Sr₃(PO₄)₂-based phosphor showing the highest emission intensity. Full article

There is growing emphasis on lightweight and energy-efficient metallic materials, with multicomponent alloying (MCA) being one strategy to achieve this. This was combined with the inherently lightweight magnesium (Mg) as the base metal. Two Mg-based MCAs, namely Mg-71MCA and Mg-80MCA (Mg-10Li-9Al-6Zn-4Si and Mg-10Li-6Al-2Zn-2Si, respectively, wt.%), with density in the range of 1.55–1.632 g/cc akin to plastics were synthesized via the Disintegrated Melt Deposition method in this work. The effects of cryogenic treatment (CT) at –20 °C, 80 °C, and –196 °C (LN) on the physical, microstructural, thermal, and mechanical properties were systematically evaluated. CT resulted in densification, significant grain refinement (up to a 27.9% reduction in grain diameter after LN treatment), alterations in crystallographic texture, and notable changes to secondary phases—namely, an increased precipitate area fraction. These led to enhanced mechanical performance such as damping capacity, microhardness, and compressive response (most apparent for Mg-71MCA with 12.1%, 6.7%, and 1.6% increase in yield strength, ultimate compressive strength, and energy absorbed, respectively, after RF20 treatment), coupled with exceptional ductility (>80% strain without fracture), which is superior to pure Mg and commercial Mg alloys. Overall, this work showcases the potential of MCAs compared to existing conventional lightweight materials, as well as the property-enhancing/tailoring effects brought upon by different CT temperatures. This highlights the multi-faceted nature of material designs where compositional control and judicious processing parameter selection need to be both leveraged to optimize final properties, and serves as a baseline for further lightweight MCA development to meet future needs. Full article

Additive manufacturing (AM) of titanium alloys enables the production of complex, high-performance components, but the steep thermal gradients and rapid solidification involved make it challenging to control crystallographic texture and phase evolution. This review synthesizes the current understanding of how these thermal conditions influence grain morphology, texture intensity, and solid-state transformations in key alloys such as Ti-6Al-4V (Ti64), Ti-6Al-2Sn-4Zr-2Mo (Ti6242), Ti-5Al-5Mo-5V-3Cr (Ti5553), and metastable β-Ti systems processed by powder bed fusion-based processes (PBF) such as laser powder bed fusion (LPBF) and electron beam powder bed fusion (EBPBF/EBM). Emphasis is placed on mechanisms governing epitaxial columnar β-grain growth, α′ martensite formation, and the development of heterogeneous α/β distributions. The impact of processing variables on texture development and transformation kinetics is critically examined, alongside phase fractions. Across studies, AM-induced textures are consistently linked to mechanical anisotropy, with performance strongly dependent on build direction and alloy chemistry. Post-processing strategies, including tailored heat treatments and hot isostatic pressing (HIP), show clear potential to modify grain structure, reduce texture intensity, and stabilize desirable phase balances in titanium alloys. These insights highlight the emerging ability to deliberately engineer microstructures for reliable, application-specific properties in powder-based AM titanium alloys. Full article

Intermetallic alloys based on A15-type compounds, including cubic Ti₃Sb, attract increasing interest due to their tunable electronic properties and potential for surface-related functional applications. Here, the interaction of nitrogen with Ti₃Sb is systematically investigated using spin-polarized density functional theory within the GGA-PBE approximation. Nitrogen adsorption was analyzed on the Ti₃Sb (111), (100), and (110) surfaces by considering top, bridge, and hollow sites at different surface coverages. Low nitrogen coverage was found to minimize lateral adsorbate interactions, allowing reliable evaluation of single-atom adsorption energies. Among the studied configurations, nitrogen adsorption at the hollow site of the Ti₃Sb (111) surface is energetically most favorable. In addition, partial substitution of Ti or Sb atoms by nitrogen in Ti₃Sb supercells was examined to assess its effect on bulk electronic properties. Nitrogen incorporation leads to pronounced modifications of the electronic band structure, density of states, and local magnetic moments, with a strong dependence on crystallographic direction. The calculated results reveal distinct electronic anisotropies originating from direction-dependent band dispersion and associated effective carrier masses. These findings clarify the role of nitrogen in tailoring both surface and bulk electronic characteristics of Ti₃Sb and provide a theoretical basis for the targeted design of A15-type intermetallic materials for sensing, catalytic, and energy-related applications. Full article

This study examines the structural, chemical, and thermal properties of biochars from slow pyrolysis of hardwood (HW), corn cob (CC), and wheat straw (WS) at 400 °C and 700 °C, evaluating their potential in environmental and industrial applications. A combination of spectroscopic, crystallographic, thermal, and microscopic techniques was employed to monitor the degradation of biomass components and the development of the carbonaceous matrix. The results show that pyrolysis temperature has a significant impact on the properties of biochar. Higher temperatures (700 °C) increased the pH (up to 10.3 for WS700), the carbon content (e.g., 89.8% for HW700), the ash content (up to 24.8% for WS700), and the specific surface area (e.g., 306.87 m²/g for CC700) while decreasing polar functional groups and volatile matter (as confirmed by FTIR). SEM showed enhanced porosity at 700 °C, which was supported by BET analysis. XRD and Raman showed increased graphitization and structural order with temperature, especially for HW and CC biochars, while WS biochars retained mineral components like SiO₂ and CaCO₃. TGA analysis showed improved thermal stability at 700 °C only for biochar derived from wheat straw, while HW and CC biochars showed similar total mass loss regardless of pyrolysis temperature. These biochars exhibit high potential for soil remediation (high pH), water purification (large surface area), and carbon storage (high aromaticity), with HW700 and CC700 also suitable for high-temperature industrial applications due to their stability. Full article

The aim of this study was to investigate the molecular interactions of heparin, diclofenac, and their supramolecular complexes with cyclooxygenase enzymes (COX-1 and COX-2) using computational docking techniques. Diclofenac is a widely used nonsteroidal anti-inflammatory drug (NSAID) that inhibits COX isoforms, whereas heparin is a polyanionic glycosaminoglycan with established anticoagulant and emerging anti-inflammatory properties. Supramolecular association between these agents may modulate their physicochemical behavior and target engagement. Molecular modeling, dual-drug docking, and molecular dynamics (MD) simulations were employed to characterize the interactions of heparin, diclofenac, and pre-formed heparin–diclofenac complexes with COX-1 and COX-2. Geometry optimization and lipophilicity (logP) estimates were obtained using HyperChem, while protein–ligand docking was performed in HEX using crystallographic COX structures from the Protein Data Bank. Docking poses were analyzed in Chimera, and selected complexes were refined through short MD simulations. Pre-formed heparin–diclofenac assemblies exhibited markedly enhanced docking scores toward both COX isoforms compared with single ligands. Binding orientation strongly influenced affinity: for COX-1, the heparin–diclofenac configuration yielded the most favorable interaction, whereas for COX-2 the diclofenac–heparin configuration was preferred. Both assemblies adopted binding modes distinct from free diclofenac, suggesting cooperative electrostatic and hydrophobic contacts at the enzyme surface. Supramolecular complexation also altered calculated logP values relative to the individual compounds. MD simulations supported the relative stability of the top-ranked complex–COX assemblies. These findings indicate that heparin–diclofenac assemblies may enhance and reorganize predicted COX interactions in a configuration-dependent manner and illustrate the utility of dual-drug docking for modeling potential synergistic effects. Such insights may inform the design of localized or topical formulations, potentially incorporating non-anticoagulant heparin derivatives, to achieve effective COX inhibition with reduced systemic exposure. However, the results rely on simplified heparin fragments, legacy docking tools, and short MD simulations, and should therefore be interpreted qualitatively. Experimental studies will be essential to confirm whether such supramolecular assemblies form under physiological conditions and whether they influence COX inhibition in vivo. Full article

As one of the polymorphs of the gallium oxide family, ε gallium oxide (ε-Ga₂O₃) demonstrates promising potential in high-power electronic devices and solar-blind photodetection applications. However, the synthesis of pure-phase ε-Ga₂O₃ remains challenging through low-energy consumption methods, due to its metastable phase of gallium oxide. In this study, we have fabricated pure-phase and highly oriented ε-Ga₂O₃ thin films on c-plane sapphire substrates via thermal atomic layer deposition (ALD) at a low temperature of 400 °C, utilizing low-reactive trimethylgallium (TMG) as the gallium precursor and ozone (O₃) as the oxygen source. X-ray diffraction (XRD) results revealed that the in situ-grown ε-Ga₂O₃ films exhibit a preferred orientation parallel to the (002) crystallographic plane, and the pure ε phase remains stable following a post-annealing up to 800 °C, but it completely transforms into β-Ga₂O₃ once the thermal treatment temperature reaches 900 °C. Notably, post-annealing at 800 °C significantly enhanced the crystalline quality of ε-Ga₂O₃. To evaluate the optoelectronic characteristics, metal–semiconductor–metal (MSM)-structured solar-blind photodetectors were fabricated using the ε-Ga₂O₃ films. The devices have an extremely low dark current (<1 pA), a high photo-to-dark current ratio (>10⁶), a maximum responsivity (>1 A/W), and the optoelectronic properties maintained stability under varying illumination intensities. This work provides valuable insights into the low-temperature synthesis of high-quality ε-Ga₂O₃ films and the development of ε-Ga₂O₃-based solar-blind photodetectors for practical applications. Full article

N-oxides are emerging as versatile tools for modulating peptide conformation due to their strong proton-accepting ability and distinct electronic properties. In this study, we report the first crystallographic evidence that an N-oxidized peptide (NOP 5) containing a proline residue forms an intramolecular six-membered hydrogen bond between the N-oxide oxygen and an adjacent amide proton. This conformational motif is not restricted to proline-containing sequences: NMR spectroscopic analyses (including DMSO-d₆ titration, VT-NMR, NOE, and concentration-dependent studies) reveal that NOPs 7 and 9, in which proline is replaced by glycine, adopt the same hydrogen-bonded ring structure in aprotic solvents. Remarkably, this conformation persists even in protic solvent (CD₃OH), indicating the robustness of the N-oxide-induced hydrogen bond. DFT calculations further support the experimental findings and rationalize the conformational preferences of NOPs 5 and 7. These results establish N-oxide as a potent and generalizable constraint for stabilizing peptide secondary structures, offering a new strategy for the design of peptidomimetics with tunable rigidity and solvent stability. Full article

In this work, iron aluminide coatings (FeAl and Fe₃Al) were developed on carbon steel substrates using the laser cladding process with mixtures of elemental iron and aluminum powders, aiming at protecting anodic pins in Soderberg electrolytic cells against oxidation and corrosion at high temperatures. These components operate under atmospheres rich in CO₂, alumina dust, and intense thermal cycles. The influence of processing parameters on the microstructure, phase formation, and mechanical properties of the coatings was investigated. X-ray diffraction confirmed the formation of the FeAl phase with a B2 ordered structure, while the expected D0₃ ordering in Fe₃Al was not detected, likely due to crystallographic texture effects. Microstructural analysis, optical and scanning electron microscopy, revealed dense coatings with good metallurgical bonding to the substrate and low porosity, being the conditions of 3.5 kW with 3 mm/s resulted in the best quality coatings. The FeAl coatings exhibited microhardness values of approximately 400 HV, whereas the Fe₃Al coatings showed values around 350 HV, indicating a significant improvement compared to the carbon steel substrate. These results demonstrate that laser cladding is an effective technique for producing iron aluminide coatings with potential application for corrosion and wear protection of anodic pins in Soderberg electrolytic cells. Full article

With the growing demand for durable and corrosion-resistant materials in advanced Li-ion battery cases, super duplex stainless steels (SDSSs) have emerged as promising candidates due to their excellent mechanical and electrochemical properties. This study aims to investigate how the ferrite and austenite phase balance in SDSS EN 1.4501 affects the microstructural and electrochemical behavior of Ag coatings, tailored for next-generation battery enclosure applications. Ag coatings were deposited to PVD (to 1 μm) on SDSS EN 1.4501 substrates with varying ferrite (from 32 vol.% to 70 vol.%) and austenite ratios (from 56 vol.% to 30 vol.%) to evaluate the influence of phase balance on coating performance. Microstructural analysis was performed using field emission scanning electron microscopy (FE-SEM, mag x 1000), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD, from 20° to 80°), which provided insights into surface morphology, crystallographic texture, and phase distribution. Electrochemical characteristics were assessed through open circuit potential (OCP), and potentiodynamic polarization in a simulated corrosive environment. The results showed that a balanced duplex microstructure promoted superior Ag coating adhesion, grain refinement, and uniform phase distribution. Furthermore, the electrochemical analyses indicated enhanced corrosion resistance and passivation layer stability in volume fraction balanced substrates, as evidenced by more noble OCP values (form −0.06 V to −0.11 V), and potentiodynamic polarization value (higher corrosion potential (from 0.08 V to 0.10 V), and lower corrosion current densities (from 3 × 10⁻⁷ A/cm² to 4 × 10⁻⁷ A/cm²)). These findings demonstrate that optimizing the phase balance in SDSS is critical for achieving high-performance Ag coated surfaces, offering significant potential for durable and corrosion-resistant Li ion battery casing applications. Full article

Advancements in deep learning have revolutionized materials discovery by enabling predictive modeling of complex material properties. However, single-modal approaches often fail to capture the intricate interplay of compositional, structural, and morphological characteristics. This study introduces a novel multimodal deep learning framework for enhanced material property prediction, integrating textual (chemical compositions), tabular (structural descriptors), and image-based (2D crystal structure visualizations) modalities. Utilizing the Alexandriadatabase, we construct a comprehensive multimodal dataset of 10,000 materials with symmetry-resolved crystallographic data. Specialized neural architectures, such as FT-Transformer for tabular data, Hugging Face Electra-based model for text, and TIMM-based MetaFormer for images, generate modality-specific embeddings, fused through a hybrid strategy into a unified latent space. The framework predicts seven critical material properties, including electronic (band gap, density of states), thermodynamic (formation energy, energy above hull, total energy), magnetic (magnetic moment per volume), and volumetric (volume per atom) features, many governed by crystallographic symmetry. Experimental results demonstrated that multimodal fusion significantly outperforms unimodal baselines. Notably, the bimodal integration of image and text data showed significant gains, reducing the Mean Absolute Error for band gap by approximately 22.7% and for volume per atom by 22.4% compared to the average unimodal models. This combination also achieved a 28.4% reduction in Root Mean Squared Error for formation energy. The full trimodal model (tabular + images + text) yielded competitive, and in several cases the lowest, error metrics, particularly for band gap, magnetic moment per volume and density of states per atom, confirming the value of integrating all three modalities. This scalable, modular framework advances materials informatics, offering a powerful tool for data-driven materials discovery and design. Full article