Search Results (65)

Boron nitride is considered a promising material for solid-state hydrogen storage due to its high thermal and chemical stability up to ~1000 °C, depending on the atmosphere, as well as its ability to form defect-rich structures with enhanced sorption activity. Despite the growing interest in modified BN systems, systematic studies on the effect of multicomponent modification induced by the addition of carbon, titanium, and aluminum on the structural and phase evolution of boron nitride during high-energy mechanical alloying remain limited to date. In this work, the structural-phase and morphological changes in boron nitride-based composites modified by the addition of carbon, titanium, and aluminum, synthesized by high-energy mechanical alloying, were investigated. The structural state and morphology of the materials were analyzed using X-ray diffraction, scanning electron microscopy, particle size analysis, and thermal analysis. It is shown that mechanical alloying leads to a progressive breakdown of the layered hexagonal BN structure and the formation of an amorphous-like, defect-rich state without the formation of new crystalline phases. The main stage of amorphization occurs within 30–60 min, after which structural disordering reaches saturation. Increasing the mechanical alloying time to 120 min does not result in significant changes in the phase state; however, it is accompanied by a reduction in agglomeration and the formation of a more homogeneous powder morphology, characterized by narrower particle size distributions, smoother particle surfaces, and more uniform spatial dispersion of components. It was established that the nature of the added component significantly influences the kinetics of structural transformations: carbon accelerates amorphization, titanium intensifies fragmentation and defect accumulation, whereas aluminum exhibits a stabilizing effect. In multicomponent BN–C–Ti–Al systems, a synergistic combination of these effects is observed, leading to the formation of metastable, partially amorphous structures. Based on a comprehensive analysis of structural and morphological data, the optimal mechanical alloying time was determined to be 120 min, providing a saturated amorphous-like structural state combined with improved microstructural homogeneity. The obtained defect-rich boron nitride structures can be considered a promising basis for further studies in the field of solid-state hydrogen storage. Full article

Starch–polyphenol interactions play a critical role in regulating the structural organization and thermal behavior of starch-based systems. In this study, maize starches with different amylose contents were used to systematically investigate how tea polyphenol (TP) complexation influences starch structure and thermal stability. Starch–TP complexes were prepared under thermal-induced conditions and characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). TGA results showed that increasing amylose content slightly reduced the thermal stability of native starches, whereas TP incorporation significantly enhanced thermal resistance, particularly in high-amylose systems. XRD analysis indicated that TP complexation did not affect the crystal structure of starch but led to a pronounced reduction in relative crystallinity, with low-amylose complexes exhibiting predominantly amorphous behavior and high-amylose complexes retaining partial nanocrystalline organization. FTIR spectra revealed reduced short-range molecular order and strengthened hydrogen bonding interactions after TP binding. DSC analysis demonstrated increased gelatinization temperatures accompanied by decreased enthalpy changes, reflecting restricted molecular mobility and delayed solvation of nanocrystalline domains. SEM observations further showed a transition toward denser and more interconnected micro–nano structures with increasing amylose content. Overall, TP preferentially interacts with amylose-rich regions through non-covalent interactions, promoting structural reorganization and enhanced thermal stability of the starch matrix. These findings provide new insight into amylose-dependent starch–polyphenol interactions and offer guidance for designing thermally stable starch-based functional materials. Full article

Post-annealing treatments constitute a simple and cost-effective strategy to tailor the structure and photocatalytic performance of polymeric carbon nitride (PCN). In this work, PCNs synthesized from melamine and urea were subjected to post-annealing at 580 °C under air and CO₂ atmospheres to elucidate the role of hydrogen bonding, as well as other structural modifications induced by oxidizing atmospheres, on photocatalytic water splitting. Comprehensive structural, chemical, and textural characterization (XRD, FTIR spectroscopy, XPS, SSNMR, HRTEM, BET, TGA, and UV–Vis DRS) reveals that post-annealing induces markedly different effects depending on the precursor. For melamine-derived PCN, the treatment selectively disrupts hydrogen bonds between melon strands without introducing nitrogen vacancies, amorphization, or framework shortening. This structural rearrangement increases surface area, reduces particle size, slightly widens the band gap, and enhances water–framework interactions, resulting in a twofold improvement in the hydrogen evolution rate (HER), reaching ~3300 µmol h⁻¹ g·cat⁻¹ under visible-light irradiation. In contrast, urea-derived PCN undergoes only minor structural modifications, including slight exfoliation and possible nitrogen deficiency, which do not translate into a measurable enhancement of photocatalytic activity. These results demonstrate that selective hydrogen-bond disruption is a key factor governing charge transport and photocatalytic efficiency in PCN. Importantly, the optimized melamine-derived PCN achieves HER values comparable to those of urea-derived PCN while maintaining a substantially higher synthesis yield, highlighting its potential for scalable solar hydrogen production. Full article

Hydrogenated amorphous silicon (a-Si:H) is a mature thin-film technology for large-area devices and thin-film sensors, and its low-temperature growth via Plasma-Enhanced Chemical Vapor Deposition (PECVD) makes it particularly suitable for biomedical flexible and wearable platforms. However, the reliable integration of a-Si:H sensors on polymer substrates requires a quantitative assessment of their electrical stability under mechanical stress, since bending-induced variations may affect sensor accuracy. In this work, we provide a quantitative, direction-dependent evaluation of the static-bending robustness of both single-doped a-Si:H layers and complete p-i-n junction stacks on polyimide (Kapton^®), thereby linking material-level strain sensitivity to device-level functionality. First, n- and p-doped a-Si:H layers were deposited on 50 µm thick Kapton^® and then structured as two-terminal thin-film resistors to enable resistivity extraction under bending conditions. Electrical measurements were performed on multiple samples, with the current path oriented either parallel (longitudinal) or perpendicular (transverse) to the bending axis, and resistance profiles were determined as a function of bending radius. While n-type layers exhibited limited and mostly gradual variations, p-type layers showed a stronger sensitivity to mechanical stress, with a critical-radius behavior under transverse bending and a more progressive evolution in the longitudinal one. This directional response identifies a practical bending condition under which doped layers, particularly p-type films, are more susceptible to strain-induced degradation. Subsequently, a linear array of a-Si:H p-i-n sensors was fabricated on Kapton^® substrates with two different thicknesses (25 and 50 µm thick) and characterized under identical bending conditions. Despite the increased strain sensitivity observed in the single-layers, the p-i-n diodes preserved their rectifying behavior down to the smallest radius tested. Indeed, across the investigated radii, the reverse current at −0.5 V remained consistent, confirming stable junction operation under bending. Only minor differences, related to substrate thickness, were observed in the reverse current and in the high-injection regime. Overall, these results demonstrate the mechanical robustness of stacked a-Si:H junctions on polyimide and support their use as sensors for wearable biosensing architectures. By establishing a quantitative, orientation-aware stability benchmark under static bending, this study supports the design of reliable a-Si:H flexible sensor platforms for curved and wearable surfaces. Full article

To obtain data on the effects of ozonolysis on the structural and dynamic parameters of ultrafine fibers based on the binary compositions of poly-(3-hydroxybutyrate) (PHB) and polyvinylpyrrolidone (PVP) with varying ratios of polymer components ranging from 0/100 to 100/0 mass%, produced by electrospinning, a study was conducted. The morphology and structural–dynamic characteristics of the ultrafine fibers were examined. Comprehensive research was carried out, combining thermophysical measurements (DSC), dynamic measurements using an electron paramagnetic resonance (EPR) technique, scanning electron microscopy, and infrared spectroscopy. The influence of the mixture’s composition and ozonolysis on the degree of crystallinity of PHB and the molecular mobility of the TEMPO radical (tetramethylpiperidine-1-oxyl) in the amorphous regions of the PHB/PVP fiber material was demonstrated. The low-temperature maximum on the DSC thermograms provided information about the fraction of hydrogen bonds in the mixed compositions, allowing for the enthalpy of thermal destruction of these bonds in both the original and oxidized samples to be determined. The study showed significant changes in the degree of crystallinity of PHB, the enthalpy of hydrogen bond destruction, molecular mobility, moisture absorption of the compositions, and the activation energy of rotational diffusion in the amorphous regions of the PHB/PVP mixed compositions. It was established that within the 50/50% PHB/PVP ratio, an inversion transition occurs from the dispersion material to the dispersion medium. Ozonolysis induces a sharp change in the material’s structure. The conducted research provided the first opportunity to assess the impact of ozonolysis on the structural and dynamic characteristics of PHB/PVP ultrafine fibers at a molecular level. These materials may serve as a therapeutic system for controlled drug delivery. Full article

Background/Objectives: Recurrent oral ulceration (ROU) is the most prevalent disorder of the oral mucosa, affecting approximately 20% of the global population. Current therapies are limited by adverse effects and high recurrence rates. Ai-Fen, enriched in the anti-inflammatory monoterpenoid L-borneol (54.3% w/w), exhibits therapeutic potential but suffers from poor aqueous solubility and low bioavailability. This study aimed to improve the physicochemical properties and in vivo efficacy of Ai-Fen through the preparation of solid dispersions. Methods: Ai-Fen solid dispersions (AF-SD) were prepared by a melt-fusion method using polyethylene glycol 6000 (PEG 6000) as the carrier. An L₉(3³) orthogonal design was employed to optimize three critical parameters: drug-to-carrier ratio, melting temperature, and melting duration. The resulting dispersions were systematically characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). A chemically induced ROU model in rats (n = 8 per group) was established to evaluate the effects of AF-SD on ulcer area, serum inflammatory cytokines (TNF-α, IL-6), vascular endothelial growth factor (VEGF) levels, and histopathological outcomes. Results: The optimal formulation was obtained at a drug-to-carrier ratio of 1:2, a melting temperature of 70 °C, and a melting time of 5 min. Under these conditions, L-borneol release increased 2.5-fold. DSC and PXRD confirmed complete conversion of Ai-Fen to an amorphous state, while FTIR revealed a 13 cm⁻¹ red shift in the O-H stretching band, indicating hydrogen-bond formation. In vivo, AF-SD reduced ulcer area by 60.7% (p < 0.001) and achieved a healing rate of 74.16%. Serum TNF-α and IL-6 decreased by 55.5% and 49.6%, respectively (both p < 0.001), whereas VEGF increased by 89.6% (p < 0.001). Histological analysis confirmed marked reduction in inflammatory infiltration, accelerated re-epithelialization (score 2.50), and a 5.9-fold increase in neovascularization. Conclusions: AF-SD markedly enhanced the bioavailability of Ai-Fen through amorphization and accelerated ROU healing, likely via dual mechanisms involving suppression of nuclear factor kappa-B (NF-κB)-mediated inflammation and promotion of angiogenesis. This formulation strategy provides a promising approach for modernizing traditional herbal medicines. Full article

Tungsten trioxide (WO₃) exhibits complementary optical and electrical responses toward hydrogen, yet the interplay between interfacial stress, crystal phase stabilization, and gasochromic/chemiresistive performance remains insufficiently understood. In this work, WO₃ films were grown on four single-crystal oxide substrates to systematically tune interfacial stress and thereby modulate the resulting crystal phase, microstructure, and exposed facets. θ–2θ diffraction revealed that WO₃ adopts a monoclinic phase on YAlO₃ and SrLaAlO₄, whereas a high-temperature orthorhombic phase is stabilized on LaAlO₃ (LAO) and SrTiO₃ due to stronger interfacial constraint. Compared with the amorphous quartz reference, the single-crystal substrates significantly enhanced both gasochromic and chemiresistive responses. In particular, the orthorhombic WO₃/LAO film exhibited an electrical response of 1.97 × 10⁴ (R_air/R_H2), an optical transmittance changed of 12.7%, and an electrical response time of 1 s toward 2% H₂ at 80 °C, far exceeding the monoclinic and amorphous counterparts. The combined effects of stress-induced phase stabilization, film orientation, and hydrogen diffusion pathways are shown to govern the non-monotonic sensing trends among different substrates. These findings elucidate the structural origin of hydrogen sensitivity in WO₃ and provide guidance for stress-engineered design of high-performance gasochromic and chemiresistive sensors. Full article

Amyloid fibrillization represents an effective strategy for extending and enhancing protein function, particularly for the delivery of hydrophobic active substances. In this study, oat globulin (OG) and its fibrils were complexed with quercetin (Que) to construct the delivery system, and ultrasonic pretreatment was applied during fibril preparation to explore the promoter of complex formation. The results demonstrated that complexation with Que induced a dose-dependent static quenching of the intrinsic fluorescence of the protein/fibrils, with hydrophobic interactions and tryptophan residues being the primary interaction forces and the main fluorescence quenching groups, respectively. In comparison, OG fibrils prepared with ultrasound pretreatment (UOGF) exhibited the strongest encapsulation and loading capacity for Que, ranging from 97.16% at a mass ratio of 200:1 to 42.48% at a ratio of 25:1. Subsequently, complexes were prepared with a ratio of 50:1. Structural analysis revealed that Que primarily interacts with the protein/fibril carriers through hydrogen bonds and hydrophobic interactions, inducing structural changes and ultimately being encapsulated in an amorphous form within the composite material. Additionally, Que promoted the mutual aggregation and cross-linking of protein/fibril units, leading to increased hydrodynamic diameter and zeta-potential. Moreover, UOGF-Que showed the greatest improvement in the thermal stability and the photostability of Que, and enhancing the bioaccessibility. These findings provide valuable insights into using ultrasound as an auxiliary measure for fibril self-assembly to enhance the application potential of fibrils, especially the delivery of hydrophobic functional substances. Full article

Ultrashort pulsed laser annealing is an efficient technique for crystallizing amorphous semiconductors with the possibility to obtain polycrystalline films at low temperatures, below the melting point, through non-thermal processes. Here, a multilayer structure consisting of alternating amorphous silicon and germanium films was annealed by mid-infrared (1500 nm) ultrashort (70 fs) laser pulses under single-shot and multi-shot irradiation conditions. We investigate selective crystallization of ultrathin (3.5 nm) a-Ge non-hydrogenated films, which are promising for the generation of highly photostable nanodots. Based on Raman spectroscopy analysis, we demonstrate that, in contrast to thicker (above 10 nm) Ge films, explosive stress-induced crystallization is suppressed in such ultrathin systems and proceeds via thermal melting. This is likely due to the islet structure of ultrathin films, which results in the formation of nanopores at the Si-Ge interface and reduces stress confinement during ultrashort laser heating. Full article

Transition metal dichalcogenides (TMSs), exemplified by molybdenum disulfide (MoS₂), exhibit significant potential as alternatives to noble metals (e.g., Pt) for the hydrogen evolution reaction (HER). However, conventional synthesis methods of MoS_x often suffer from active site loss, harsh reaction conditions, or undesirable oxidation, limiting their practical applicability. The development of MoS_x with high-density active sites remains a formidable challenge. Herein, we propose a novel strategy employing [Mo₃S₁₃]²⁻ clusters as precursors to construct three-dimensional amorphous MoS_x nanosheets through optimized hydrothermal and solvent evaporation-induced self-assembly approaches. Comprehensive characterization confirms the material’s unique amorphous lamellar structure, featuring preserved [Mo₃S₁₃]²⁻ units and engineered interlayer dislocations that facilitate enhanced electron transfer and active site exposure. This work not only establishes [Mo₃S₁₃]²⁻ clusters as effective building blocks for high-performance MoS_x catalysts, but also provides a scalable and environmentally benign synthesis route for the large-scale production of such nanostructured a-MoS_x. Our findings facilitate the rational design of non-noble HER catalysts via structural engineering, with broad implications for energy conversion technologies. Full article

Based on the photoconductive effect of photosensitive films, a designed light pattern was projected onto a hydrogenated amorphous silicon (a-Si:H) photosensitive chip to generate virtual light-induced electrodes for cellular electrical detection. To obtain high-quality cellular signals, this study aims to explore the effect of electrical excitation on a-Si:H photosensitive chip. Firstly, the electrochemical impedance spectroscopy (EIS) and volt-ampere characteristics of the a-Si:H photosensitive chip were characterized. EIS data were fitted to extract equivalent circuit models (ECMs) for both the chip and system. Then analog experiments were performed to verify the ECMs, and the results were consistent with the circuit simulation. Finally, applied alternating current (AC) or direct current (DC) signals to the chip and recorded the electrical signals of the cultured cardiomyocytes on the a-Si:H photosensitive chip. The results demonstrated that applying a high-frequency small AC signal to the chip reduced the background noise of the system by approximately 85.1%, and applying a DC bias increased the amplitude of the detection signal by approximately 142.7%. Consequently, the detection performance of the a-Si:H photosensitive chip for weak bioelectrical signals was significantly enhanced, advancing its applicability in cellular electrophysiological studies. Full article

In our previous study, we observed that sodium chloride (NaCl) influences the formation of amyloid fibrils (AFs) by gluten in cooked wheat noodles. However, the underlying mechanisms of NaCl’s effect on AF formation during the cooking process remain unclear. This study systematically investigates the impact of NaCl concentration (0–2.0%, w/w) and cooking time (0–7 min) on AF formation. ThT fluorescence and Congo red confirmed AF formation across all NaCl concentration levels. At low NaCl concentrations, Na⁺/Cl⁻ shielding reduced electrostatic repulsion, enabling ordered β-sheet stacking, yielding long fibrils (1193 nm) with high β-sheet content (41.5%), dense cross-β structures, and elevated hydrophobicity (H₀ = 9980). Stable zeta potential and gradual particle growth (376 to 1193 nm) supported controlled elongation. Conversely, high NaCl concentrations disrupted hydrogen bonding, forming shorter fibrils (820 nm) with reduced β-sheets (28.9%) and lower hydrophobicity (H₀ = 5923). Rapid ThT kinetics (df/dt = 77,535 FU/min) and SE-HPLC profiles suggest that elevated concentrations of NaCl inhibit AF formation while inducing the generation of amorphous aggregates. These findings clarify the balance between ionic shielding and hydrophobic interactions in AF assembly, offering strategies to optimize noodle texture. Future studies should address the digestibility and health implications of salt-modulated AFs for functional food applications. Full article

Background/Objectives: Tegoprazan (TPZ) is a potassium-competitive acid blocker (P-CAB) used to treat conditions such as gastroesophageal reflux disease, peptic ulcer, and Helicobacter pylori infection. It exists in three solid forms: amorphous, Polymorph A, and Polymorph B. This study investigates the molecular basis of polymorph selection, focusing on conformational bias and solvent-mediated phase transformations (SMPTs). Methods: The conformational energy landscapes of two TPZ tautomers were constructed using relaxed torsion scans with the OPLS4 force field and validated by nuclear Overhauser effect (NOE)-based nuclear magnetic resonance (NMR). Hydrogen-bonded dimers were analyzed using DFT-D. Powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), solubility, and slurry tests were conducted using methanol, acetone, and water. Kinetic profiles were modeled with the Kolmogorov–Johnson–Mehl–Avrami (KJMA) equation. Results: Polymorph A was thermodynamically stable across all analyses. Both amorphous TPZ and Polymorph B converted to A in a solvent-dependent manner. Methanol induced direct A formation, while acetone showed a B → A transition. Crystallization was guided by solution conformers and hydrogen bonding. Conclusions: TPZ polymorph selection is governed by solution-phase conformational preferences, tautomerism, and solvent-mediated hydrogen bonding. DFT-D and NMR analyses showed that protic solvents favor the direct crystallization of stable Polymorph A, while aprotic solvents promote the transient formation of metastable Polymorph B. Elevated temperatures and humidity accelerate polymorphic transitions. This crystal structure prediction (CSP)-independent strategy offers a practical framework for rational polymorph control and the mitigation of disappearing polymorph risks in tautomeric drugs. Full article

Hydrogenated amorphous carbon (a-C:H) films are widely valued for their excellent mechanical strength and low friction, but their performance significantly degrades at elevated temperatures, limiting practical applications in aerospace environments. In this work, we aimed to enhance the high-temperature tribological behavior of a-C:H films through controlled silicon (Si) doping. A series of a-C:H:Si films with varying Si contents were fabricated via direct current magnetron sputtering, and their microstructure, mechanical properties, and friction behavior were systematically evaluated from room temperature up to 400 °C. Results show that moderate Si doping (8.3 at.%) substantially enhances hardness and wear resistance, while enabling ultralow friction (as low as 0.0034) at 400 °C. This superior performance is attributed to the synergistic effects of transfer layer formation, preferential Si oxidation, and tribo-induced graphitization. This study provides new insights into the high-temperature lubrication mechanisms of Si-doped a-C:H films and demonstrates the critical role of Si content optimization, highlighting a viable strategy for extending the thermal stability and lifespan of solid-lubricating films. Full article

The widespread adoption of electric vehicles (EVs) has introduced new challenges in drivetrain lubrication, particularly concerning electrical corrosion, frictional wear, and hydrogen embrittlement. While polyalphaolefin (PAO)-based lubricants are commonly used, they struggle under high-speed and high-torque conditions. In contrast, polyphenyl ether (PPE)-based lubricants offer superior wear resistance and effectively suppress hydrogen generation, making them promising for EV applications. This study examines the effects of current direction and magnitude on tribofilm formation and frictional behavior in a PPE-lubricated environment. The results show that PPE exhibits unique tribofilm adhesion characteristics influenced by electrical conditions, unlike PAO. Surface analysis reveals that the tribofilm mainly consists of amorphous carbon, and friction under an electrical bias induces PPE oxidation, with oxidation products forming more readily at the positive electrode. Tribofilm formation correlated with increased friction and wear, particularly under currents of 10 mA or higher. Although PPE is more sensitive to electrical influences than PAO, it exhibits excellent wear resistance and maintains a low coefficient of friction even under electrification. This suggests that PPE could be suitable for lubrication in electrical environments and may serve as a promising lubricant for EV drive systems and similar applications. Full article