Search Results (19)

Boron carbide (B4C) is a widely recognized ceramic prized for its remarkable properties, including exceptional hardness, low density, and excellent chemical and mechanical stability. To date, limited research has explored the possible health risks associated with B4C nanoparticles (B4C-NPs). This study utilized a Caenorhabditis elegans (C. elegans) in vivo model to investigate the toxicological effects of B4C-NPs at concentrations of 40, 80, 160, and 320 mg/L. Larval nematodes were subjected to prolonged exposure, and their locomotion (head thrashing and body bending), reproduction (brood size), development (body length), lifespan, and gene expression (linked to oxidative stress, metal detoxification, apoptosis, and neurotransmitter synthesis) were assessed. Regarding survival rates, lethality was significantly increased to 5.41% at 320 mg/L of B4C-NPs and lifespan was significantly shortened across all concentrations compared with the controls. Development and reproduction showed slight reductions between 40 and 320 mg/L, while locomotion was markedly impaired at the doses from 80 to 320 mg/L. Gene expression related to antioxidants, apoptosis, cell cycle arrest, neurotransmitter synthesis, and metal detoxification rose significantly at 160–320 mg/L in C. elegans, suggesting that B4C-NPs may induce reproductive and neurological toxicity, delay development, reduce lifespan, and potentially cause genotoxicity in C. elegans. Full article

Boron Neutron Capture Therapy (BNCT) is a therapeutic approach used to treat malignancies that are difficult to localise and typically inoperable. This therapy involves two stages: the administration of the boron (¹⁰B) isotope, which selectively enters cancer cells without affecting healthy tissue, followed by irradiation of the tumour with a neutron beam. In this study, boron carbide (B₄C), a ceramic material with exceptional physical and chemical properties, was used as a nanoparticle platform for BNCT. The surface of the boron carbide nanoparticles was optimised by modifying them with compounds such as dextrin, dextran T70, sorbitol, lysine, and arginine. Boron carbide was synthesised directly from boron and carbon and then subjected to grinding, washing, and centrifugation. The unmodified and modified samples were analysed for their particle size, zeta potential, and toxicity against glioblastoma T98G cells. Additionally, FTIR spectroscopy confirmed the successful surface modifications. The results demonstrate that boron carbide, as a ceramic material, can be effectively functionalised with biocompatible compounds. Among the tested modifications, B₄C-dextrin and B₄C-dextran T70 exhibited the highest toxicity towards cancer cells, demonstrating the potential of ceramic platforms in biomedical applications. Full article

Single and multiple pull-out properties of a nano-processed para-aramid fabric structure were investigated. The nano pull-out behavior exhibited three distinct regions, namely crimp extension, interlacement rupture, and stick-slip. Multiple yarn pull-out tests demonstrated a significantly higher pull-out force compared to single-yarn pull-out, primarily attributed to the incorporation of nanoparticles. Furthermore, it was observed that an increase in fabric length resulted in an approximately linear increase in both yarn crimp extension and pull-out force. The highest pull-out force was obtained in the nano-hexagonal boron carbide (nh-B₄C, 0.3%) para-aramid structure, followed by multiwalled carbon nanotube (MWCNT, 0.3%) para-aramids. This is because of the enhancement of filament-to-filament friction, especially in the interlacement zone of fabric, alongside the cumulative frictional interactions among the nanoparticles. Additionally, the findings highlight an improvement in crimp extension energy absorption facilitated by nanoparticle incorporation in soft fabric. Notably, the improvement in the energy absorption capacity of yarns within the fabric, without disintegration, is considered significant at this stage. These results indicate a promising potential for performance enhancement in prospective soft ballistic applications. Full article

This work investigates the impact of friction stir processing (FSP) on the microstructure and mechanical characteristics of AA 6061 alloy and its composites, which are strengthened with boron nitride nanoparticles and vanadium carbide microparticles. Composite samples were created using different proportions of reinforcing particles, including mono and hybrid composites. The efficacy of FSP as a technological method for enhancing the grain size of AA 6061 alloy and its composites has been proven. Adding reinforcing particles led to enhanced grain refinement, especially when using VC particles, which demonstrated greater efficacy than BN particles; thus, mono composite AA6061/VC shows the highest percentage reduction (94.29%) in grain size. Hybrid composites with a higher concentration of VC particles exhibited a more symmetrical microhardness profile. The microhardness of hybrid composites with a larger concentration of VC particles (40 vol.%BN + 60 vol.%VC) shows the most significant enhancement, with an increase of 51.61%. The Young’s and shear modulus of all composite samples processed by (FSP) had greater values than the wrought AA 6061 alloy. The investigated composite samples, especially 60% BN and 40% VC, enhanced the tribological properties of AA6061 and reduced the wear rate by about 52%. The observed characteristics may be due to BN and VC particles in the hybrid compost. This is because these particles effectively prevent grain elongation and inconsistent movement. This is because reinforcing particles can be tailored to have specific properties for specific applications. Full article

Nanoparticles composed of inorganic boron-containing compounds represent a promising candidate as ¹⁰B carriers for BNCT. This study focuses on the synthesis, characterization, and assessment of the biological activity of composite nanomaterials based on boron carbide (B₄C). Boron carbide is a compelling alternative to borated molecules due to its high volumetric B content, prolonged retention in biological systems, and low toxicity. These attributes lead to a substantial accumulation of B in tissues, eliminating the need for isotopically enriched compounds. In our approach, B₄C nanoparticles were included in composite nanostructures with ultrasmall superparamagnetic nanoparticles (SPIONs), coated with poly (acrylic acid), and further functionalized with the fluorophore DiI. The successful internalization of these nanoparticles in HeLa cells was confirmed, and a significant uptake of ¹⁰B was observed. Micro-distribution studies were conducted using intracellular neutron autoradiography, providing valuable insights into the spatial distribution of the nanoparticles within cells. These findings strongly indicate that the developed nanomaterials hold significant promise as effective carriers for ¹⁰B in BNCT, showcasing their potential for advancing cancer treatment methodologies. Full article

Cavitation erosion poses a significant challenge in fluid systems like hydraulic turbines and ship propellers due to pulsed pressure from collapsing vapor bubbles. To combat this, various materials and surface engineering methods are employed. In this study, nano and micro scale particles of silicon carbide (SiC) or boron carbide (B₄C) were incorporated as reinforcement at 6% and 12% ratios, owing to their exceptional resistance to abrasive wear and high hardness. Microparticles were incorporated to assess the damage incurred during the tests in comparison to nanoparticles. Wear tests were conducted on both bulk samples and coated aluminum sheets with a 1mm of composite. Additionally, cavitation tests were performed on coated aluminum tips until stability of mass loss was achieved. The results indicated a distinct wear behavior between the coatings and the bulk samples. Overall, wear tended to be higher for the coated samples with nanocomposites than bulk, except for the nano-composite material containing 12% SiC and pure resin. With the coatings, higher percentages of nanometric particles correlated with increased wear. The coefficient of friction remained within the range of 0.4 to 0.5 for the coatings. Regarding the accumulated erosion in the cavitation tests for 100 min, it was observed that for all nanocomposite materials, it was lower than in pure resin. Particularly, the composite with 6% B₄C was slightly lower than the rest. In addition, the erosion rate was also lower for the composites. Full article

Boron carbide is one of the hardest materials in the world which can be synthesized by various methods. The most common one is a carbothermic or magnesiothermic reduction of B₂O₃ performed at high temperatures, where the obtained powder still requires grinding and purification. The goal of this research is to present the possibility of synthesizing B₄C nanoparticles from elements via vapor deposition and modifying the morphology of the obtained powders, particularly those synthesized at high temperatures. B₄C nanoparticles were synthesized in the process of direct synthesis from boron and carbon powders heated at the temperature of 1650 °C for 2 h under argon and characterized by using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction analysis, and dynamic light scattering measurements. The physicochemical characteristics of B₄C nanoparticles were determined, including the diffusion coefficients, hydrodynamic diameter, electrophoretic mobilities, and zeta potentials. An evaluation of the obtained B₄C nanoparticles was performed on several human and mouse cell lines, showing the relation between the cytotoxicity effect and the size of the synthesized nanoparticles. Assessing the suitability of the synthesized B₄C for further modifications in terms of its applicability in boron neutron capture therapy was the overarching goal of this research. Full article

Inorganic nanoparticles of boron-rich compounds represent an attractive alternative to boron-containing molecules, such as boronophenylalanine or boranes, for BNCT applications. This work describes the synthesis and biological activity of multifunctional boron carbide nanoparticles stabilized with polyacrylic acid (PAA) and a gadolinium (Gd)-rich solid phase. A fluorophore (DiI) was included in the PAA functionalization, allowing the confocal microscopy imaging of the nanoparticles. Analysis of the interaction and activity of these fluorescent Gd-containing B₄C nanoparticles (FGdBNPs) with cultured cells was appraised using an innovative correlative microscopy approach combining intracellular neutron autoradiography, confocal, and SEM imaging. This new approach allows visualizing the cells, the FGdBNP, and the events deriving from the nuclear process in the same image. Quantification of ¹⁰B by neutron autoradiography in cells treated with FGdBNPs confirmed a significant accumulation of NPs with low levels of cellular toxicity. These results suggest that these NPs might represent a valuable tool for achieving a high boron concentration in tumoral cells. Full article

Complications of chronic non-healing wounds led to the emergence of nanotechnology-based therapies to enhance healing, facilitate tissue repair, and prevent wound-related complications like infections. Here, we design alpha lipoic acid (ALA) conjugated hexagonal boron nitride (hBN) and boron carbide (B₄C) nanoparticles (NPs) to enhance wound healing in human dermal fibroblast (HDFa) cell culture and characterize its antimicrobial properties against Staphylococcus aureus (S. aureus, gram positive) and Escherichia coli (E. coli, gram negative) bacterial strains. ALA molecules are integrated onto hBN and C₄B NPs through esterification procedure, and molecular characterizations are performed by using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV-vis spectroscopy. Wound healing and antimicrobial properties are investigated via the use of cell viability assays, scratch test, oxidative stress, and antimicrobial activity assays. Based on our analysis, we observe that ALA-conjugated hBN NPs have the highest wound-healing feature and antimicrobial activity compared to ALA-B₄C. On the other hand, hBN, ALA-B₄C, and ALA compounds showed promising regenerative and antimicrobial properties. Also, we find that ALA conjugation enhances wound healing and antimicrobial potency of hBN and B₄C NPs. We conclude that the ALA-hBN conjugate is a potential candidate to stimulate regeneration process for injuries. Full article

The boron carbide (B₄C) nanoparticles doping mesophase pitch (MP) was synthesized by the in-situ doping method with tetrahydrofuran solvent, and the corresponding MP−based carbon fibers (CFs) were successfully prepared through the melt−spinning, stabilization, carbonization and graphitization processes. The structural evolution and properties of boron−containing pitches and fibers in different processes were investigated for exploring the effect of B₄C on mechanical, electrical and thermal properties of CFs. The results showed that the B₄C was evenly dispersed in pitch fibers to provide active sites of oxygen, resulting in a homogeneous stabilization and ameliorating the split−ting microstructures of CFs. Moreover, the thermal conductivity of B1−MP−CF prepared with 1 wt.% B₄C increased to 1051 W/m•K, which was much higher than that of B0−MP−CF prepared without B₄C (659 W/m•K). While the tensile strength of B₄C−doped CFs was lower than that of pristine CFs. In addition, a linear relationship equation between the graphite microcrystallite parameter (I_D/I_G) calculated from Raman spectra and the thermal conductivity (λ) calculated according to the electrical resistivity was found, which was beneficial to understand the thermal properties of CFs. Therefore, the doping B₄C nanoparticles in MP did play a significant role in reducing the graphitization temperatures due to the boron catalytic graphitization but decreasing the mechanical properties due to the introduction of impurities. Full article

Aluminum-based metal matrix composites with single or multiple ceramic reinforcements are finding application in the aerospace and automobile industries. In this research work, novel AA7150-B4C (aluminium7150 alloy–Boron carbide) nanocomposites were successfully fabricated, through the liquid metallurgy route via stir casting method, with the incorporation of B4C nanoparticles with different weight percentages using a novel sequence of a vortex technique and a double stir casting process with ultrasonication. The formed composites have been thoroughly studied for microstructure refinement, nano-particulate distribution, and bonding with the matrix by making use of the optical microscopy (OM) and scanning electron microscopy (SEM) studies (respectively). In addition, the composites were analyzed for the density, porosity, and elemental composition. Further, the composites were tested for the investigation of mechanical properties, like micro-hardness and tensile strength, to investigate the influence of ultrasonic vibration on the arrangement of B4C nano-particulates. The analysis indicated that the mechanical properties of the AA7150-B4C nanocomposites in as-cast condition significantly improved with a gain of 57.7% in strength and 24.5% in hardness compared to the native AA7150 material. Full article

Improving the mechanical durability and wear resistance of aluminum alloys is a research challenge that can be solved by their reinforcement with ceramics. This article is concerned with the improvement of the mechanical properties and wear resistance of the AA2024 aluminum alloy surface. Surface composites were prepared by incorporating a hybrid of heavy particles (tantalum carbide (TaC), light nanoparticles, and boron nitride (BN)) into the AA2024 alloy using the friction stir process (FSP) approach. Three pattern holes were milled in the base metal to produce the composites with different volume fractions of the reinforcements. The effects of the FSP and the reinforcements on the microstructure, mechanical properties, and wear resistance are investigated. In addition to the FSP, the reinforced particles contributed to greater grain refinement. The rolled elongated grains became equiaxed ultrafine grains reaching 6 ± 1 µm. The refinement and acceptable distribution in the reinforcements significantly improved the hardness and wear resistance of the produced composites. Overall, the hardness was increased by 60% and the wear resistance increased by 40 times compared to the base alloy. Full article

In this paper, AA5250 aluminum sheets are reinforced with boron nitride (BN), silicon carbide (SiC), aluminum oxide (Al₂O₃), and vanadium carbide (VC). The nanocomposites metal matrix are manufactured using friction stir processing (FSP). A novel analytical comparison based on an assessment of mechanical, physical properties and the cost of manufactured materials was conducted to help the engineers and designers choose the most economically feasible nanocomposite. The results revealed extra grain refining for all composites in the stirred zone (SZ) due to the Zener-pinning mechanism. The smallest grain size was obtained in AA5250/BN, and it decreased 20 times that of the base metal (BM). The highest wear resistance was achieved in AA5250/SiC, followed by AA5250/VC and AA5250/BN. The lowest coefficient of friction was obtained for AA5250/BN due to the self-lubrication property of BN; which was μ = 0.28. SiC AA5250 had the highest hardness, increasing three times more than the base metal in terms of its hardness. There was a detailed discussion of the probable explanations for the improvements. However, the outstanding characteristics of the BN nanoparticles, the AA5250/BN was reported to be lower than the AA5250/SiC. In comparison, the AA5250/SiC nanocomposite exhibits the optimum value due to its fitting for different properties relative to the cost. Full article

The aim of the work was to study the interaction between boron-rich boron carbide nanoparticles and selected tumor and immune phagocytic cells. Experiments were performed to investigate the feasibility of the application of boron carbide nanoparticles as a boron carrier in boron neutron capture therapy. Boron carbide powder was prepared by the direct reaction between boron and soot using the transport of reagents through the gas phase. The powder was ground, and a population of nanoparticles with an average particle size about 80 nm was selected by centrifugation. The aqueous suspension of the nanoparticles was functionalized with human immunoglobulins or FITC-labeled human immunoglobulins and was then added to the MC38 murine colon carcinoma and to the RAW 264.7 cell line of mouse macrophages. Flow cytometry analysis was used to determine interactions between the functionalized boron carbide nanoparticles and respective cells. It was shown that B₄C–IgG nanoconjugates may bind to phagocytic cells to be internalized by them, at least partially, whereas such nanoconjugates can only slightly interact with molecules on the cancer cells’ surface. Full article

We report on the fabrication of fractal dendrites using laser-induced melting of aluminum alloys. We target boron carbide (B${}_4$C), which is one of the most effective radiation-absorbing materials characterized by a low coefficient of thermal expansion. Due to the high fragility of B${}_4$C crystals, we were able to introduce its nanoparticles into a stabilization aluminum matrix of AA385.0. The high-intensity laser field action led to the formation of composite dendrite structures under the effect of local surface melting. Modelling the dendrite cluster growth confirms its fractal nature and sheds light on the pattern behavior of the resulting quasicrystal structure. Full article