Search Results (5)

Magnetite (Fe₃O₄) nanoparticles are biocompatible, non-toxic, and easily functionalized. Coating them with mesoporous silica (mSiO₂) offers high surface area, pore volume, and tunable surface chemistry for drug loading. In this study, Fe₃O₄ magnetic nanoparticles were synthesized and coated with mSiO₂ shells enriched with calcium ions (Ca²⁺), aiming to enhance bioactivity for bone regeneration and tissue engineering. Different synthesis routes were tested to optimize shell formation Their characterization confirmed the presence of a crystalline Fe₃O₄ core with partial conversion to maghemite (Fe₂O₃) post-coating. The silica shell was mostly amorphous and the optimized samples exhibited mesoporous structure (type IVb). Calcium incorporation slightly altered the magnetic properties without significantly affecting core crystallinity or particle size (11.68–13.56 nm). VSM analysis displayed symmetric hysteresis loops and decreased saturation magnetization after coating and Ca²⁺ addition. TEM showed spherical morphology with some agglomeration. MTT assays confirmed overall non-toxicity, except for mild cytotoxicity at high concentrations in the Ca²⁺-enriched sample synthesized by a modified Stöber method. Their capacity to induce human periodontal ligament cell osteogenic differentiation, further supports the potential of Fe₃O₄/mSiO₂/Ca²⁺ core–shell nanoparticles as promising candidates for bone-related biomedical applications due to their favorable magnetic, structural, and biological properties. Full article

The article offers a reexamination of Ovid’s story of Philomela and Procne, with an emphasis on revenge and lament as two responses to acts of wrongdoing and loss. My analysis begins by exploring philosophical and psychoanalytic perspectives, mainly from Nietzsche and Freud, which are usually thought of as complete opposites: revenge is considered active and violent, whereas lament is passive and paralyzed. However, upon revising Ovid’s tale of unimaginable suffering answered by both lament and revenge, I show that in Ovid’s story, they appear as interconnected and dependent on each other. Initially, Philomela appears as the passive, lamenting sister, while Procne appears as the angry, vengeful one. Nevertheless, as the narrative unfolds, the roles of the sisters change. Through the characters of Philomela and Procne, Ovid presents a compelling account in which these two responses can be seen as mirror images of the same phenomenon, rather than diametrically opposed binaries. Full article

We present the results of a twofold experimental and computational study of (0001) GaN/AlN multilayers forming pseudomorphic superlattices. High-Resolution Transmission Electron Microscopy (HRTEM) shows that heterostructures with four c-lattice parameters thick GaN Quantum Wells (QW) are misfit-dislocation free. Accurate structural data are extracted from HRTEM images via a new methodology optimizing the residual elastic energy stored in the samples. Total energy calculations are performed with several models analogous to the experimental QWs with increasing thicknesses of GaN, whereas this of the AlN barrier is kept fixed at n = 8 c-lattice parameters. With vanishing external stresses, minimum energy configurations of the studied systems correspond to different strain states. Linear elasticity accurately yields the corresponding lattice parameters, suppressing the need for on-purpose total energy calculations. Theoretically justified parabolic fits of the excess interfacial energy yield the values of interfacial stress and elastic stiffness as functions of the GaN QW thickness. Total species-projected densities of states and gap values extracted from there allow deciphering the effect of the evolving strain on the electronic structure of the superlattice. It is found that the gap energy decreases linearly with increasing the strain of the QW. These results are briefly discussed in the light shed by previous works from the literature. Full article

The use of strained substrates may overcome indium incorporation limits without inducing plastic relaxation in InGaN quantum wells, and this is particularly important for short-period InGaN/GaN superlattices. By incorporating elastic strain into these heterostructures, their optoelectronic behavior is modified. Our study employed density functional theory calculations to investigate the variation in the band-gap energy of short-period InGaN/GaN superlattices that comprise pseudomorphic quantum wells with a thickness of just one monolayer. Heterostructures with equibiaxially strained GaN barriers were compared with respective ones with relaxed barriers. The findings reveal a reduction of the band gap for lower indium contents, which is attributed to the influence of the highly strained nitrogen sublattice. However, above mid-range indium compositions, the situation is reversed, and the band gap increases with the indium content. This phenomenon is attributed to the reduction of the compressive strain in the quantum wells caused by the tensile strain of the barriers. Our study also considered local indium clustering induced by phase separation as another possible modifier of the band gap. However, unlike the substrate-controlled strain, this was not found to exert a significant influence on the band gap. Overall, this study provides important insights into the behavior of the band-gap energy of strained superlattices toward optimizing the performance of optoelectronic devices based on InGaN/GaN heterostructures. Full article

Hemocompatible nanoparticles with reactive oxygen species (ROS) scavenging properties for titanium implant surface coatings may eliminate implant failure related to inflammation and bacterial invasion. Cerium (Ce) is a rare earth element, that belongs to the lanthanide group. It exists in two oxidation states, Ce⁺³ and Ce⁺⁴, which contribute to antioxidant, catalytic, antibacterial, and ROS-scavenging properties. The purpose of the present study was to synthesize ceria nanoparticles and to evaluate their hemocompatibility and ROS scavenging properties. The synthesis of Ce-NPs was performed via the sol-gel method, and five different ratios of cerium precursors to gelatin were evaluated. Their characterization was achieved through FTIR, XRD, SEM, and TEM. Hemocompatibility and ROS analysis were evaluated at different concentrations with human erythrocytes. The morphology and size distribution were certified by TEM and the cubic CeO₂ fluorite structure was identified by selected area electron diffraction and high-resolution TEM. The particle size of the lowest Ce concentration presented a mean diameter of 10 nm. At concentrations of <500 μg/mL, no hemolytic effect was observed. At the highest concentrations, no hemolytic behavior was recorded for samples with the highest Ce precursor, which also presented ROS scavenging properties (10–50% reduction in ROS). These properties make those CeO₂ NPs unique candidates as nanofillers or nanocoatings with antibacterial properties. Full article