Search Results (2,455)

In this study, the R452A refrigerant used in refrigerated trucks is investigated through a multiscale approach combining thermodynamic and molecular-level analyses. The performance of the vapor compression refrigeration system is evaluated using energy and exergy analyses to assess system efficiency and identify irreversibilities. At the molecular level, Density Functional Theory (DFT) is employed to investigate the electronic structure and bonding characteristics of refrigerant components. This approach enables a detailed understanding of molecular properties that influence macroscopic thermodynamic behavior in refrigeration systems. Full article

This study applied density functional theory (DFT) to investigate gas-sensitive devices based on Pt- and Pd-doped SnS₂ monolayers, exploring their adsorption and sensing performance on four characteristic gases generated under normal operating or fault conditions of transformer oil. The adsorption behaviors and underlying sensing mechanisms of four gases on pristine and modified SnS₂ were systematically elucidated. The results reveal that Pt/Pd incorporation triggers a transition from weak physisorption to robust chemisorption. Compared to intrinsic SnS₂, the decorated monolayers exhibit dramatically augmented adsorption energies and accelerated interfacial charge transfer for all target molecules. Crucially, noble metal modification fundamentally modulates the electronic structure of the SnS₂ lattice, endowing the material with exceptional recognition specificity for distinguishing different gas species. These theoretical insights establish Pt- and Pd-SnS₂ as highly promising candidates for advanced DGA sensors, providing a robust materials design strategy for the condition monitoring of critical electrical infrastructure. Full article

Bandstructure methods occupy a central place in the physics of nanostructures, and the multiband $\mathit{k}·\mathit{p}$ theory of Luttinger, Kohn, and Kane has served as one of the most widely used computational frameworks for modelling electronic states and energies in low-dimensional semiconductor systems for several decades. Despite its broad success, the theory harbours a fundamental mathematical difficulty that has been largely overlooked: the multiband Luttinger–Kohn Hamiltonians are non-elliptic partial differential operators for the overwhelming majority of common III–V and III-nitride crystalline materials, a fact that violates the axiomatic requirements of quantum mechanics and is the root cause of the long-standing problem of spurious solutions. In this paper, we derive ellipticity conditions rigorously for the $6\times 6$, $8\times 8$, and $14\times 14$ zinc-blende Hamiltonians, demonstrating that non-ellipticity affects a substantially larger class of materials than previously reported. We develop and justify a systematic parameter rescaling procedure for the $8\times 8$ Kane Hamiltonian and obtain admissible parameter sets for GaAs, AlAs, InAs, GaP, AlP, InP, GaSb, AlSb, InSb, GaN, AlN, and InN. The inversion-asymmetry parameter B is shown to play an essential and previously unrecognized role in maintaining ellipticity, and it is used to optimize the bandstructure fit of the rescaled parameter sets. Analysis of several known $14\times 14$ models reveals structural sources of non-ellipticity, pointing to the need for a revision of perturbative assumptions regarding out-of-basis band contributions. The consistent parametrization framework developed here provides the rigorous mathematical foundation required by inverse design methodologies, AI-enhanced electronic structure calculations, and data-driven multifidelity approaches in nanoscience and nanotechnology. Full article

The structural, electronic, optical, transport and photocatalytic properties of the BTe/PtS₂ vdW heterojunction are investigated by the density functional theory approach. The results reveal that applying the tensile effect can significantly impact the material’s properties. The bandgap values of BTe, PtS₂ and BTe/PtS₂ vdW heterojunction are 1.599 eV, 1.756 eV and 1.19 eV, respectively. The bandgap decreases as the percentage of applied tensile effect increases. Moreover, the photocatalytic water decomposition of BTe/PtS₂ vdW heterojunction is significantly broadened in the pH range compared with that of the two monolayers. In conclusion, the BTe/PtS₂ vdW heterojunction can be used as an efficient photocatalytic material for optoelectronic devices and photocatalysis. Full article

Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2DM) are major global health burdens that share interconnected pathological mechanisms involving impaired insulin signaling, metabolic stress, and chronic neuroinflammation. This study applied an integrative systems biology and atomistic simulation framework to investigate bioactive compounds from Caesalpinia sappan L. targeting shared molecular regulators linking AD and T2DM. Network topology analysis identified four central hub genes, STAT3, SRC, HSP90AA1, and TP53, representing key regulatory nodes involved in inflammatory signaling, kinase regulation, proteostasis, and cellular stress responses. Compound-specific interaction analysis revealed distinct target preferences among phytochemical subclasses. Protosappanin B showed strong binding toward both STAT3 and HSP90α, whereas flavonols including quercetin and rhamnetin exhibited high affinity for SRC, and the chalcone derivative sappanchalcone preferentially interacted with TP53. Atomistic molecular dynamics simulations and MM-PBSA calculations supported stable protein ligand interactions and favorable binding energetics, while density functional theory analysis indicated electronic properties consistent with sustained intermolecular interactions. Collectively, these findings suggest that structurally distinct subclasses of C. sappan phytochemicals converge on complementary regulatory hubs within the shared AD and T2DM molecular network, supporting coordinated multi-target modulation of interconnected inflammatory, kinase signaling, proteostasis, and cellular stress pathways underlying AD–T2DM comorbidity. Full article

This paper proposes a source-level electromagnetic interference suppression strategy for high-voltage inverters that uses a series-connected IGBT topology and discrete staircase voltage shaping. From an information-theoretic perspective, the staircase shaping transforms chaotic wideband switching noise into a deterministic harmonic structure, thereby reducing the spectral entropy of the EMI source. This information optimization is achieved using a CPLD-based sequential gate drive circuit, which eliminates the need for complex active gate profiling algorithms. Experimental results obtained using a 1140 V explosion-proof motor drive platform demonstrate harmonic attenuation of 4–16 dB μV within a 2 MHz band. Importantly, this targeted entropy reduction occurs alongside a 68.7% reduction in active-region switching losses, suggesting a concurrent decrease in local thermodynamic entropy production during switching transients. Increasing spectral determinism and relaxing requirements for subsequent physical filters effectively lower the conditional entropy of the overall electromagnetic environment. Leveraging the structural flexibility of series IGBTs, this method provides a practical, low-complexity solution and establishes a novel framework between power electronics and information theory for electromagnetic compatibility. Full article

Coal matrix pores are critical sites for gas storage and migration, ensuring effective gas drainage, safe coal mining and reliable evaluation of pore structures. To investigate coal matrix pore characteristics, this study examines coal samples from the Xiaobaodang and Sangshuping collieries (Samples 1 and 2, respectively) using focused ion beam scanning electron microscopy. Datasets were developed through systematic data acquisition, preprocessing and labelling, and the MDFA-DeepLabv3+ model was trained for pore segmentation. Spatial pore size distribution characteristics were derived by integrating 3D reconstruction theory. The final evaluation metrics yielded IoU, Dice, PA, Precision, and Recall values of 81.63%, 89.89%, 98.51%, 89.43%, and 90.34%, respectively. Sample 1 and Sample 2 have broadly similar coordination numbers, Euler numbers and tortuosity values, yet they show distinct differences in the proportion of pores by volume and total pore quantity. These findings provide a theoretical basis for the accurate evaluation of coal matrix pore characteristics and the optimisation of gas drainage design. Full article

Oxalic acid is extensively used in industrial chemical processes, purification systems, hydrometallurgical operations, and advanced oxidation environments where rapid and environmentally sustainable analytical methodologies are increasingly required for process monitoring and quality control. In this study, a micro-Raman spectroscopy methodology was developed for the direct quantification of oxalic acid in aqueous systems at moderate-to-high concentrations (0.079–0.793 M). The analytical strategy was based on the integrated Raman response of the carbonyl stretching region (1700–1750 cm⁻¹), selected due to its strong concentration-dependent behavior, spectral definition, and reduced interference from the aqueous matrix. The proposed methodology demonstrated excellent analytical performance, including high linearity (R² > 0.998), satisfactory precision, and reliable concentration-dependent reproducibility throughout the evaluated concentration range. To evaluate operational robustness, matrix-matched standards incorporating temperature variation (25–40 °C), turbidity (0–57 mg/L), dissolved Ca²⁺ (0–58 mg/L), and dissolved Fe³⁺ (0–7 mg/L) were prepared to simulate chemically perturbed industrial environments. Principal Component Analysis (PCA) demonstrated that the carbonyl vibrational region retained organized concentration-dependent spectral behavior despite operational perturbations. Partial Least Squares (PLS) regression models developed under these matrix-informed conditions preserved strong predictive capability (R² ≈ 0.997), while preliminary prediction of process-related samples yielded excellent agreement between predicted and reference concentrations (R² = 0.990). Although operational perturbations produced substantial attenuation of Raman intensity, particularly at lower concentration levels, the carbonyl Raman band remained spectrally detectable and analytically interpretable throughout all evaluated conditions. Electronic-structure analysis using Natural Bond Orbital (NBO) and Atoms-in-Molecules (AIM) methodologies demonstrated that the strong analytical behavior of the ν(C=O) vibrational mode is associated with enhanced electron-density localization, covalent stabilization, and favorable polarizability characteristics of the carbonyl bond. The combined experimental, chemometric, and computational results demonstrate the feasibility of matrix-informed micro-Raman spectroscopy as a rapid, reagent-free, and operationally robust methodology for oxalic acid monitoring in chemically perturbed aqueous industrial systems. Full article

Pd-decorated Janus ZrSSe monolayers provide a promising platform for adsorption-coupled electronic modulation in two-dimensional materials. Using first-principles density functional theory, we systematically investigate the structural stability, electronic properties, and adsorbate-induced electronic response of Pd-modified Janus ZrSSe. The results show that Pd is most stably anchored at the hollow site on the S-terminated surface, with a formation energy of $-1.45$ eV, while substitutional incorporation remains energetically unfavorable even after HSE06 refinement. Compared with pristine ZrSSe, Pd decoration markedly strengthens the interaction with adsorbates, leading to strong chemisorption for CO ($-1.026$ eV) and C₂H₂ ($-0.748$ eV), whereas H₂ remains comparatively weakly bound ($-0.258$ eV). Electronic-structure analysis reveals that CO induces the most pronounced perturbation because of strong orbital hybridization between Pd 4d states and C/O 2p states, resulting in the largest band-edge modulation among the three adsorbates. More importantly, biaxial strain provides an effective external degree of freedom for continuously tuning the electronic structure: tensile strain widens the band gap, whereas compressive strain systematically narrows it and ultimately drives a semiconductor-to-metal transition at sufficiently large compression. These findings establish Pd-decorated Janus ZrSSe as a strain-tunable electronic material in which adsorption, orbital hybridization, and band-edge evolution are intimately coupled, offering fundamental insights into controllable electronic modulation in polar two-dimensional systems. Full article

Whether copper fundamentally alters Mo-centered redox thermodynamics or mainly tunes hydrogen adsorption in Ni–Mo electrocatalysts under alkaline hydrogen evolution reaction (HER) conditions remains unresolved. Density functional theory calculations combined with a field-corrected computational hydrogen electrode framework are used to evaluate the thermodynamic stability of H₃Mo, H₃MoOH, H₂Mo(OH)₂, and MoO(OH)₃ on Cu(111) and Ni(111) and to construct surface Pourbaix diagrams under electrochemical conditions. The results show that substrate identity reorganizes the redox stabilization hierarchy of these Mo intermediates. Across the examined conditions, at least one of H₃Mo, H₃MoOH, or MoO(OH)₃ is thermodynamically favored over H₂Mo(OH)₂ on both surfaces. However, only Cu(111) exhibits measurable pH-dependent free-energy shifts, reaching 0.25 eV on the reversible hydrogen electrode scale. The magnitude of this electrostatic modulation is comparable to the intrinsic substrate-dependent relative Gibbs free-energy differences, suggesting that Cu reshapes Mo redox thermodynamics rather than merely weakening hydrogen binding strength. Electronic structure and vibrational analyses further show that Cu(111) preferentially weakens Mo–O interactions, whereas Ni(111) more strongly perturbs Mo–H bonding in hydrogen-rich complexes. Overall, these results establish that substrate identity governs the electrostatic modulation of Mo redox thermodynamics under alkaline HER conditions and provide mechanistic insight into substrate effects relevant to Cu-containing Ni–Mo systems. Full article

In this study, the stability, electronic, structural, and fracture toughness, and mechanical properties of the Half-Heusler(HH) alloys MnCoSb, MnCoAs, MnCoP, and MnNiSb were comprehensively investigated using first-principles calculations based on density functional theory (DFT). The calculated results reveal that all four alloys exhibit half-metallic characteristics, characterized by the presence of a substantial band gap in the spin-down channel. The phonon spectra and negative formation energies confirm that these alloys possess both dynamic and thermodynamic stability. The Born criteria further validate the structural stability in terms of mechanical properties. Three-dimensional representations of the Young’s modulus, bulk modulus, and shear modulus for the four alloys indicate that MnCoP exhibits the most pronounced anisotropy. The overall fracture toughness of the alloys ranges from 1.58 MPa·m^1/2 to 2.63 MPa·m^1/2, which falls within the typical range for half-metallic materials, albeit at the lower end, attributable to the relatively ductile nature of the four alloys. Although the two methods yield different absolute values, the explicit crack model (Method I) is considered more reliable for anisotropic systems because it directly simulates crack propagation and accounts for local relaxations, while the empirical formula (Method II) provides a useful reference for high-throughput screening. Among the alloys, MnCoSb demonstrates a superior mechanical performance, with K_IC values of 2.63 MPa·m^1/2 and 1.58 MPa·m^1/2 and brittleness indices M of 8.97 and 14.94, indicating excellent damage tolerance compared to the other three alloys. In contrast, MnCoP exhibits higher brittleness and lower mechanical reliability, with K_IC values of 2.00 MPa·m^1/2 and 1.63 MPa·m^1/2 and higher M values of 13.83 and 16.99. This study provides quantitative predictions of fracture toughness and establishes a relationship between microscopic and mechanical properties. These findings offer a theoretical foundation for the application of damage-tolerant HH alloys in fields such as spintronics and magnetism. Full article

Background: Digital health technologies are increasingly integral to healthcare delivery worldwide; however, successful adoption depends on more than technological availability. In nursing, readiness is particularly important because digital systems increasingly shape documentation, communication, decision support, and care delivery. Within the context of Saudi Arabia’s healthcare transformation, doctoral nursing students are positioned as future educators, clinicians, and leaders whose perceptions can provide insight into digital health readiness and preparation. Aim: This study aimed to explore doctoral nursing students’ perceptions of their readiness to adopt digital health technologies in Saudi Arabia, guided by the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2). Methods: This exploratory, qualitative, descriptive study recruited 9 doctoral nursing students from a public university in Saudi Arabia using purposive sampling based on predefined eligibility criteria. Individual semi-structured interviews were conducted online and audio-recorded. Data were analyzed using a hybrid inductive–deductive thematic approach. UTAUT2 informed the deductive component of the analysis, while inductive coding and cross-case comparison supported theme generation. Results: Four interrelated themes were identified. First, readiness was positive but conditional, shaped by movement from openness to professional necessity, familiarity, workflow fit, and caution about the possible weakening of foundational or manual competence. Second, adoption depended on practical value and system credibility, including access, convenience, efficiency, safety, documentation integrity, accuracy, privacy, and reliability. Third, adoption was organizationally mediated through leadership, peer culture, infrastructure, implementation conditions, training, follow-up, and academic preparation. Fourth, digital health was understood as supporting, not substituting for, nursing work by reducing avoidable burden and creating more space for direct care while preserving human presence, communication, and clinical judgment. Conclusions: In this sample of doctoral nursing students, digital health readiness was positive but conditional. The findings suggest that readiness reflects a context-sensitive professional judgment shaped by educational preparation, organizational support, system credibility, workflow compatibility, and the perceived ability of digital technologies to enhance nursing work rather than replace it. Implications: The findings suggest that nursing education and practice should strengthen applied digital health competencies through simulation-based preparation, electronic documentation training, privacy and ethics education, workflow-aligned implementation, and sustained organizational support. Full article

This study aims to investigate the performance and mechanism of N′-[(E)-phenylmethylidene] furan-2-carbohydrazide (FNH), a hydrazone Schiff base, as a corrosion inhibitor for carbon steel in 1.0 M HCl. The research was conducted by coupling electrochemical testing (Tafel analysis and Impedance spectroscopy) with surface characterization (SEM and AFM) and advanced computational tools, including quantum-chemical modeling and classical molecular dynamics (MD) simulations. Tafel analysis revealed that FNH acts as a mixed-type inhibitor, concurrently slowing iron oxidation and hydrogen reduction. Impedance data showed that the Faradaic resistance grew monotonically with FNH dosage, reaching 95% protection at 1 × 10⁻⁴ M. Fitting the results to the Langmuir model indicated a joint physical–chemical anchoring pathway, further confirmed by SEM/AFM inspection which disclosed a uniform organic deposit. Quantum-chemical modeling revealed that protonated species broaden the molecule’s capacity for bidirectional electron exchange, while MD simulations on the Fe (110) slab confirmed a flat-lying geometry that maximizes heteroatom–metal contact. The consistency between laboratory observables and atomic-scale predictions provides a detailed, mechanism-oriented picture of how this organic protective layer curtails acid corrosion. Full article

This study investigates the electronic and photocatalytic properties of greenly fabricated rutile-phase titanium dioxide (bTiO₂) modified with iron vanadate (Fe/bTiO₂/VO₄) and vanadium-substituted goethite (Fe/bTiO₂/VOOH) by detailed experimental assay and density functional theory (DFT) calculations. Our analysis of the density of states (DOS), band structure, and work function reveals that both dopant systems significantly modify the electronic structure of pure rutile bTiO₂. The dye methyl orange (MO) was used as the model pollutant. During photodegradation tests, parameters such as the reaction time, solid-to-liquid ratio, initial concentrations of the photocatalyst and dye, as well as distance of the lamp from the reactor and pH were varied. Degradation kinetics follows the equation of the pseudo-first order law for both photocatalysts (k_VO4 = 0.058 min⁻¹ and k_VOOH = 0.065 min⁻¹), while degradation efficiencies of 92% and 99% were observed after 120 min at pH 3, respectively. Specifically, the DOS analysis highlights the contribution of Fe 3d and V 3d orbitals, which create new electronic states within the bandgap, facilitating charge transfer. These insights provide a strong foundation for the rational design of novel, highly efficient Fe/bTiO₂-based photocatalysts for the degradation of organic pollutants in water. Full article

The electrochemical co-conversion of CO₂ and H₂O into valuable products is a promising approach toward carbon-neutral energy systems. Alloy exsolution from perovskite lattices has emerged as an effective strategy to engineer catalytic interfaces, yet the mechanistic influence of exsolved bimetallic species on CO₂/H₂O co-electrolysis remains insufficiently clarified. To address this gap, density functional theory (DFT) calculations were performed in this study to systematically examine how NiFe alloy clusters exsolved from the LSFNO (La_0.7Sr_0.3Fe_0.9Ni_0.1O_3-δ) (111) surface modify the electronic structure of the interfacial region and promote the RWGS reaction in CO₂/H₂O co-electrolysis. Our work highlights bimetallic alloy exsolution as a powerful strategy for improving co-electrolysis catalysts and offers valuable guidance for the rational design of next-generation high-entropy oxide systems. Full article