Search Results (476)

In low-amplitude and low-frequency vibration environments, the energy harvesting efficiency of self-powered wireless sensor nodes is insufficient, limiting their long-term autonomous operation. To address this issue, a micro piezoelectric–electromagnetic hybrid energy harvester is designed, aiming to enhance energy capture efficiency through structural integration and parameter optimization. The study is conducted entirely through numerical simulations. A coaxial integrated architecture is adopted, combining a piezoelectric cantilever beam array with an electromagnetic induction module. The piezoelectric layer uses lead magnesium niobate–lead titanate (PMN-PT) solid solution material with a thickness of 0.2 mm. The electromagnetic module employs copper wire coils with a diameter of 0.08 mm, winding 1500–3000 turns, paired with N52-type neodymium–iron–boron (NdFeB) permanent magnets. To improve energy conversion efficiency, the optimization parameters include the length-to-thickness ratio of the cantilever beam, the mass of the tip mass, the number of coil turns, and the spacing of the permanent magnets. Each parameter is set at four levels for orthogonal experiments. A multi-physics coupling model is established using ANSYS Workbench 2023, covering structural dynamics, piezoelectric effects, and the electromagnetic induction module. The mesh size is set to 0.1 mm. The energy output characteristics are analyzed under vibration frequencies of 0.3–12 Hz and amplitudes of 0.2–1.0 mm. Simulation results show that the optimized hybrid harvester achieves 45% higher energy conversion efficiency than a single piezoelectric structure and 31% higher than a traditional separated hybrid structure within the 0.3–12 Hz low-frequency range. Under a 6 Hz frequency and 0.6 mm amplitude, the output power density reaches 3.5 mW/cm³, the peak open-circuit voltage is 4.1 V, and the peak short-circuit current is 1.3 mA. Under environmental conditions of 20–88% humidity and −15–65 °C temperature, the device maintains over 94% stability in energy output. After 1.2 million vibration cycles, structural integrity remains above 96%, and energy conversion efficiency decreases by no more than 5%. The proposed coaxial hybrid structure and multi-parameter orthogonal optimization method effectively enhance energy harvesting performance in low-amplitude, low-frequency environments. The simulation design parameters and analysis procedures provide a reference for the development of similar micro hybrid energy harvesters and support the performance optimization of self-powered wireless sensor nodes. Full article

The global shortage of ³He resources has created an urgent need for alternative neutron detection technologies in applications such as national security, neutron scattering, and nuclear energy. This study designed and developed a zero-dimensional planar high-efficiency thermal neutron detector based on a boron-lined multi-wire proportional chamber (MWPC) employing two distinct efficiency-enhancement approaches: a multilayer structure and grazing-incidence geometry. For ease of use, a sealed detector has been developed, eliminating the need for gas cylinders. Geant4 simulations were utilized to optimize the ${\mathrm{B}}_4\mathrm{C}$ thickness of conversion layer and evaluate $\gamma$-ray sensitivity. Prototype detectors were fabricated and experimentally validated at the 20th beamline (BL20) of China Spallation Neutron Source (CSNS). Simulation results indicate that the optimal ${\mathrm{B}}_4\mathrm{C}$ thickness varies with layer count and neutron wavelength, measuring approximately 2.0 µm at 1.8 Å and 1.5 µm at 4 Å for a 10-layer structure, with $\gamma$-ray sensitivity below $5\times {10}^{-6}$. Experimental measurements demonstrate that a five-layer detector achieved neutron detection efficiencies of 28.0 ± 1.5% at 4.78 Å and 17.8 ± 1.8% at 2.87 Å, while a two-layer detector at 11.5° incidence attained 19.2% and 11.7%. This research lays the groundwork for developing large-area, high-efficiency, position-sensitive neutron detectors. Full article

Lithium-ion batteries suffer from severe capacity fading and start-up failure at low temperatures owing to restricted Li⁺ transport and deteriorated interfacial kinetics. To enable rapid and safe activation under such conditions, this study designs a microwave-driven dual-layer leakage-proof composite phase-change module (EPG–BN–CF–PAG), comprising an epoxy–graphene–boron nitride outer encapsulation and a ceramic fiber–boron nitride porous inner scaffold that adsorbs a paraffin–graphene phase-change core. The synergy between the dense outer shell and the internal adsorption framework affords excellent shape stability, with an enthalpy retention exceeding 95% and no visible leakage after 20 heating–cooling cycles. Owing to the strong microwave-absorption capability of graphene, the module can be rapidly heated from −10 °C to ~60 °C within 60 s while establishing a homogeneous and stable temperature field. Combined simulations and experiments show that the module efficiently transfers heat to a lithium-ion cell, raising its temperature from −10 °C to ~30 °C within 60 s and thus bringing it into a practical operating window. Electrochemical impedance spectroscopy further reveals that the thermally induced activation markedly improves interfacial kinetics, reducing the bulk resistance from 500 Ω to 30 Ω and the charge-transfer resistance from 800 Ω to 30 Ω. This microwave-driven phase-change heating strategy features ultrafast response, excellent anti-leakage performance, and favorable thermal properties, providing an engineering-feasible thermal-management solution for the rapid cold start of lithium-ion batteries under extremely low-temperature conditions. Full article

To address the high-temperature and high-cost challenges of the conventional dry oxidation process in boron diffusion for n-type tunnel oxide passivated contact solar cells, this study proposes a dry–wet–dry mixed oxidation drive-in process for fabricating p-type emitters in TOPCon solar cells. Through systematic investigation of oxidation temperature, O₂/H₂O flow ratio, and oxidation time effects on emitter performance, it is found that mixed oxidation at 1000 °C achieves comparable sheet resistance and doping profiles to dry oxidation at 1050 °C. For our newly developed mixed oxidation process, in which the oxidation temperature is 1000 °C, oxidation time is 80 min with O₂/H₂O flow ratio of 20:1, the same photoelectric conversion efficiency has been achieved. Comparing the data, the mixed oxidation process forms a dry/wet/dry three-layer SiO₂ structure, reducing the oxidation temperature by 50 °C while achieving an average efficiency of 26.02%, comparable to high-temperature dry oxidation. This process not only reduces the thermal budget of quartz tubes and extends equipment service life but also provides a feasible solution for the low-temperature manufacturing of high-efficiency TOPCon solar cells, showing significant industrial application prospects. Full article

Flame-retardant microcapsules were prepared using a urea–melamine–formaldehyde (UMF) shell and boric acid-crosslinked ammonium polyphosphate (APP) as the core to improve the dispersion stability and processing compatibility of phosphorus-based flame retardants. Thermal analysis showed that the microcapsules exhibited initial mass loss near 80 °C due to moisture evaporation and shell relaxation, while APP-related degradation occurred at higher temperatures, indicating delayed release of the core and enhanced thermal resistance through encapsulation. Scanning electron microscopy confirmed the formation of microcapsules, and morphological changes before and after combustion suggested the development of protective char layers. Boron-containing residues are expected to contribute to char stabilization through the formation of B–O–P structures during heating. The flame-retardant properties were evaluated using limiting oxygen index, smoke density, and vertical burning tests. Although the limiting oxygen index slightly decreased due to reduced accessible APP content, stable burning behavior was maintained, and characteristic char formation was observed after combustion. These results indicate that the UMF/APP microcapsules can improve thermal stability and handling of phosphorus-based flame retardants. The microencapsulation approach presented here may provide practical advantages for polymer processing and surface-coating applications. Full article

The growing use of radiation technologies has increased the need for shielding materials that are lightweight, safe, and adaptable to complex geometries. While lead remains highly effective, its toxicity and weight limit its suitability, driving interest in alternative materials. The process of 3D printing enables the rapid fabrication of customized shielding geometries; however, only limited research has focused on 3D-printed polymer composites formulated specifically for mixed photon–neutron fields. In this study, we developed a series of 3D-printable ABS-based composites incorporating tungsten (W), bismuth oxide (Bi₂O₃), gadolinium oxide (Gd₂O₃), and boron nitride (BN). Composite filaments were produced using a controlled extrusion process, and all materials were 3D printed under identical conditions to enable consistent comparison across formulations. Photon attenuation at 120 kVp and neutron attenuation using a broad-spectrum Pu–Be source (activity 4.5 × 10⁷ n/s), providing a mixed neutron field with a central flux of ~7 × 10⁴ n·cm⁻²·s⁻¹ (predominantly thermal with epithermal and fast components), were evaluated for both individual composite samples and layered (sandwich) configurations. Among single-material prints, the 30 wt% Bi₂O₃ composite achieved a mass attenuation coefficient of 2.30 cm²/g, approximately 68% of that of lead. Layered structures combining high-Z and neutron-absorbing fillers further improved performance, achieving up to ~95% attenuation of diagnostic X-rays and ~40% attenuation of neutrons. The developed materials provided a promising balance between 3D-printability and dual-field shielding effectiveness, highlighting their potential as lightweight, lead-free shielding components for diverse applications. Full article

Boron is a promising fuel, but its oxide layer impedes combustion. Alloying boron with other high-energy metals can significantly enhance its combustion performance. In this study, we sintered highly reactive lithium-containing Mg-Al-Li-B alloys using magnesium, aluminum–lithium alloy, and boron powder as raw materials. The effects of sintering temperature and holding time on the microstructure were investigated, and the combustion heat value and oxidation resistance of the alloy were tested. Results indicate that sintering temperature significantly influences phase formation: increasing temperature boosts phase content while reducing metallic phases, with 1100 °C identified as the optimal sintering temperature. Holding time had no discernible impact on the phase composition or combustion heat value of the sintered alloy. Alloying enhances material density, thereby increasing volumetric heat value. Thermal oxidation performance tests demonstrate that Li addition significantly lowers the alloy’s oxidation reaction temperature and activation energy, enhancing its reactivity. This high-heat-value, highly reactive alloy holds significant potential for application in pyrotechnics and propellants. Full article

Background: Dorsal pedicle skin flap application is a cover procedure frequently used by plastic surgeons to cover acute and chronic wounds, but preventing postoperative flap loss and disruption of the wound healing process has not yet been achieved. Injecting boron nitride during the transfer of the dorsal pedicle skin flap may increase flap survival. Objective: This study investigated the efficacy of hexagonal boron nitride (hBN) injection in enhancing the survival of pedicled skin flaps harvested from the dorsal region of rats. Method: This study employed an experimental design. A total of 24 Wistar albino rats were divided into three groups of eight each: Control (Group 1), Sham (Group 2), and Experimental (Group 3). A 27 cm² (3 cm × 9 cm) dorsal skin flap with a proximal pedicle was harvested at the level of the iliac crests, with the flap extending cranially, and then reattached. During flap transfer, no intervention was performed in Group 1, physiological saline was injected into Group 2, and hBN was injected into Group 3. After a certain period of time, sections were taken from the proximal pedicle skin flap on the dorsal side of the rats, and histochemical examination and biochemical analyses were performed on these sections. Results: In this study, it was observed that the epithelial integrity of the epidermal layer was disrupted and the epithelium was thinned in places in Group 2. Compared to Group 1, collagen fiber density was lower, collagen fiber arrangement was irregular, and mast cell density was higher. In Group 3, similar to Group 1, the epidermis and dermis layers were composed of multilayered flat keratinized epithelium, collagen fiber density was high and had a regular arrangement, and elastic fiber structure was of normal density. The TGF-β1 and MMP-1 measurement results for the three groups were compared, and no statistically significant difference was found between the groups (p > 0.05). Conclusions: The results of this study support the benefit of hBN injection in improving flap survival after proximal pedicle skin flap application on the dorsal side of rats. Although the improved healing of skin layers after flap transfer with hBN suggests that it supports cell proliferation, the mechanism of action and pathophysiology remain unclear. Full article

The continuous advancement of modern weaponry has intensified the pursuit of next-generation ballistic protection systems that integrate lightweight architectures, superior flexibility, and high energy absorption efficiency. This review provides a technological overview of current trends in the design, processing, and performance optimization of metallic, ceramic, polymeric, and composite materials for ballistic applications. Particular emphasis is placed on the role of advanced surface coatings and nanostructured interfaces as enabling technologies for improved impact resistance and multifunctionality. Conventional materials such as high-strength steels, alumina, silicon carbide, boron carbide, Kevlar^®, and ultra-high-molecular-weight polyethylene (UHMWPE) continue to dominate the field due to their outstanding mechanical properties; however, their intrinsic limitations have prompted a transition toward nanotechnology-assisted solutions. Functional coatings incorporating nanosilica, graphene and graphene oxide, carbon nanotubes (CNTs), and zinc oxide nanowires (ZnO NWs) have demonstrated significant enhancement in interfacial adhesion, inter-yarn friction, and energy dissipation. Moreover, multifunctional coatings such as CNT- and laser-induced graphene (LIG)-based layers integrate sensing capability, electromagnetic interference (EMI) shielding, and thermal stability, supporting the development of smart and adaptive protection platforms. By combining experimental evidence with computational modeling and materials informatics, this review highlights the technological impact of coating-assisted strategies in the evolution of lightweight, high-performance, and multifunctional ballistic armor systems for defense and civil protection. Full article

In recent years, polymer-based hybrid nanocomposites have emerged as promising alternatives to traditional heavy metal shields due to their low density, flexibility, and environmental safety. In this study, the synthesis of PS-PEG copolymers and the gamma radiation-shielding properties of PS-PEG/As₂O₃, PS-PEG/BN, and PS-PEG/As₂O₃/BN nanocomposites with different compositions are investigated. The goal is to find the optimal nanocomposite composition for gamma radiation shielding and dosimetry. Therefore, the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), effective atomic number, mean free path (MFP), radiation shielding efficiency (RPE), electron density, and specific gamma-ray constant were presented. Gamma rays emitted by the Eu source were detected by a high-purity germanium (HPGe) detector device. GammaVision was used to analyze the given data. Photon energy was in the vicinity of 121.8–1408.0 keV. The MAC values in XCOM simulation tools were used to compute. Gamma-shielding efficiency was increased by an increased number of NPs at a smaller photon energy. At 121.8 keV, the HVL of a composite with 70 wt% As₂O₃ NPs is 2.00 cm, which is comparable to the HVL of lead (0.56 cm) at the same energy level. Due to the increasing need for lightweight, flexible, and lead-free shielding materials, PS-b-PEG copolymer-based nanocomposites reinforced with arsenic oxide and BN NPs will be materials of significant interest for next-generation radiation protection applications. Full article

Bioactive glasses remain promising candidates for enhancing osseointegration on metallic implants. However, achieving a composition that combines controlled dissolution, cytocompatibility, and antimicrobial functionality remains an ongoing challenge. Building upon the prior structural and thermal characterization of boron-substituted 6P55 phosphosilicate glasses, this study investigates the biological consequences of incorporating 0, 5, 10, and 15 mol% B₂O₃ to determine their suitability as coatings for Ti6Al4V. Glass extracts were evaluated using L-929 fibroblast cultures (MTT assay and ImageJ-based cell counting), antimicrobial assays against Escherichia coli and Staphylococcus aureus using a semi-quantitative dilution-plating method, and SBF immersion studies to assess pH evolution, surface mineralization, and Ca/P ratio development. FTIR and SEM analyses revealed composition-dependent formation of phosphate-, carbonate-, and silicate-rich surface layers, with 5B exhibiting the most consistent early-stage hydroxyapatite-like signatures, supported by Ca/P ratios approaching the stoichiometric value. The pH measurements showed rapid alkalization for 5B and moderate buffering behavior at higher boron contents, consistent with boron-dependent modifications to network connectivity. Cytocompatibility studies demonstrated a dose- and time-dependent reduction in cell number at elevated B₂O₃ levels, whereas the 0B and 5B extracts maintained higher viability and preserved cell morphology. Antibacterial assays revealed strain-dependent and sub-lethal inhibitory effects, with E. coli exhibiting stronger sensitivity than S. aureus, likely due to differences in cell wall architecture and susceptibility to ionic osmotic microenvironment changes. When considered alongside previously published computational and physicochemical results, the biological data indicate that moderate boron incorporation (5 mol%) provides the most favorable balance between dissolution kinetics, apatite formation, cytocompatibility, and antimicrobial modulation. These findings identify the 5B composition as a strong candidate for further optimization toward bioactive glass coatings on Ti6Al4V implants. Full article

This article presents the effect of laser alloying with boron on the surface layer of iron alloys: steel and grey cast iron. The general goal of this review is to specify the main differences that can be expected after this treatment of selected iron-based alloys. Boron as an alloying element is first characterized. The effects of laser alloying are described in comparison to diffusion processing. The next section describes the effect of laser alloying with boron on the microstructure, hardness, and wear resistance of the surface layer of selected iron alloys. As a result of the conducted analysis, the most significant differences in the outcomes of laser alloying with boron, which may occur during the processing of various iron alloys, are as follows: the presence of graphite in the surface layer in the case of grey cast iron treatment and a clearly visible transition zone between the alloyed zone and the hardened zone during the treatment of grey cast iron as opposed to steel; variable depths of the modified surface layer and varied grain size in the alloy zone depending on the thermophysical properties of the material being treated. Full article

A non-standardized hypereutectic aluminum–silicon alloy, AlSi18Cu3CrMn, was developed. To refine the structure of the studied composition, a phosphorus modifier was used in an amount of 0.04 wt %, and a complex modifying treatment was applied by combining the chemical elements of phosphorus, titanium, boron and beryllium (P, 0.04 wt %; Ti, 0.2 wt %; B, 0.04 wt %; Be, 0.007 wt %). To improve the mechanical and operational properties of the alloy, it was heat-treated (T6) at a temperature of 510–515 °C before quenching, with artificial aging applied at a temperature of 210 °C for 16 h. Phosphorus-modified alloy AlSi18Cu3CrMn was quenched in water at 20 °C, and the combined modified alloy was quenched in water at temperatures of 20 °C and 50 °C. By conducting a microstructural analysis, the free Si crystals and silicon crystals in the composition of the eutectic in the alloy structure were characterized, and by conducting XRD, the presence and type of secondary phases were established. The hardness of the alloy was measured, as well as the microhardness of the α-solid solution. Static uniaxial tensile testing was carried out at normal and elevated temperatures (working temperatures of 200 °C, 250 °C and 300 °C). By using a gravimetric method, the corrosion rate of the alloy in 1 M NaCl and 1 M H₂SO₄ was calculated. The mass wear, wear intensity and wear resistance of the studied AlSi18Cu3CrMn alloy were determined during reversible reciprocating motion in the boundary-layer lubrication regime. Full article

In this study, boron was introduced into bamboo-derived porous carbon (BPC) through dry thermal treatment using boric acid. During heat treatment, boric acid was converted to B₂O₃, which subsequently interacted with the oxygen-containing surface groups of BPC, leading to the formation and evolution of B–O–B and B–C bonds. This boron-induced bonding network reconstruction enhanced π-electron delocalization and surface polarity, while maintaining the intrinsic microporous framework of BPC. Among the prepared samples, B-BPC-1 exhibited an optimized balance between the conductive domains and defect concentration, resulting in lower internal resistance and improved ion transport behavior. Correspondingly, B-BPC-1 delivered a better capacitive performance than both undoped BPC and commercial activated carbon. These results indicate that controlling boron incorporation under appropriate heat-treatment conditions effectively improves charge-transfer kinetics while maintaining a stable pore morphology. The proposed dry thermal doping method provides a practical and environmentally benign route for developing high-performance porous carbon electrodes for electric double-layer capacitor applications. Full article

Boron (B) powder is a promising high-energy fuel but suffers from inefficient combustion due to its native boron oxide (B₂O₃) passivation layer. Surface coating is a crucial strategy to overcome this limitation. In this study, core–shell structured B@NiF₂/ammonium perchlorate (AP) composite micro-units with varying mass ratios were prepared using planetary ball milling to optimize energy release and combustion performance. The optimal formulation for the ternary composite was determined to be 0.5% NiF₂, 13.3% B, and 86.2% AP. Morphological characterization revealed that NiF₂ was uniformly coated on the B particles, forming a dense shell. Thermal analysis indicated that the NiF₂ interfacial layer, through its high-temperature decomposition (NiF₂ → Ni + 2F·), released highly reactive fluorine radicals (F·) that etched the B₂O₃ layer, generating volatile boron oxyfluoride and creating void structures. This led to a maximum heat release of 8912 J/g and a reaction mass gain of 74.58%, indicating more complete combustion. The material also exhibited a minimal ignition delay of 0.618 s and the lowest ignition energy (22.17 J). Overall, the B@NiF₂/AP composite provides a novel solution for applying boron fuel in solid propellants and pyrotechnic technologies. Full article