FERNANDO BACCI EFFENBERGER
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Resumo IPEN-doc 31001 Enhancing Rhizobium performance in common bean plants through Fe3O4 nanoparticles2024 - MASUNAGA, SUELI H.; SOUZA-TORRES, ANGEL de; GOVEA-ALCAIDE, ERNESTO; GOMES-PADILLA, ERNESTO; EFFENBERGER, FERNANDO B.; ROSSI, LIANE M.; LOPEZ-SANCHEZ, RAUL; JARDIM, RENATO de F.This study investigates the effects of Fe3O4 nanoparticles (NPs) on nodulation, nitrogen fixation, and growth of common bean plants. Plants were exposed to Fe3O4 NPs, Rhizobium inoculation, and Fe3O4 NPs + Rhizobium inoculation. Results showed that treated plants exhibited improved symbiotic performance, with increased nitrogenase activity, nodule leghaemoglobin, and iron content. Additionally, the number of active nodules per plant and nodule dry weight significantly increased. Symbiotic nitrogen fixation was enhanced, leading to higher shoot and root total nitrogen content. Treatment combining Fe3O4 NPs and Rhizobium inoculation yielded the best results. Fe3O4 NPs were taken up by plants, accumulating in organs including nodules. Moreover, treated plants displayed increased root and shoot lengths, leaf area, and dry weights. Magnetization curves indicated the accumulation of Fe3O4 NPs in nodules, enhancing symbiotic performance. The study suggests a novel strategy for improving common bean growth through Fe3O4 NPs and Rhizobium inoculation, offering potential benefits for sustainable agriculture, and reducing nitrogen fertilizer use. These findings contribute to a non-genetic approach in legume research, emphasizing long-term improvements in common bean growth and symbiosis [1-2].Resumo IPEN-doc 27086 Investigation of magnetic and structural properties of CoFe2O4 nanoparticles by measuring hyperfine interactions with 111Cd2019 - MATOS, I.T.; NASCIMENTO, N.M.; CABRERA-PASCA, G.A.; EFFENBERGER, F.B.; FREITAS, R.S.; CARBONARI, A.W.Because their ability of magnetic nanoparticles (MNP) to become magnetized when exposed to an external magnetic field, which make them good candidates for biomedical applications [1]. The investigation of the magnetic and structural properties by techniques with atomic resolution, such as those based on hyperfine interactions, is, therefore, greatly useful in the study of MNP. In this work, hyperfine interactions in nanoparticles of CoFe2O4 were investigated by perturbed γ-γ angular correlation (PAC) spectroscopy using 111Cd as probe nuclei in the temperature range from 50 K to 850 K. Samples of CoFe2O4 were prepared by thermal decomposition [2]. Magnetic measurements results show a blocking temperature of 210 K and a superparamagnetic behavior at 300 K. MET measurements show that particles present well-monodispersed spherical shape with average size of 7 nm. XRD results show that samples crystallize in a single phase with the expected spinel structure. PAC spectra were fitted by a model considering two site fractions occupied by the probe nuclei. One were characterized by a single well-defined Larmor frequency with site fraction population of 47%, which was assigned to probe nuclei substituting cation sites in the core region of the particles. The other was characterized by a broad distribution quadrupole frequency with population of 53% corresponding to probe nuclei at distorted cation sites in the shell region of the particles. This assignment agrees with an expected shell/core volume ratio for particles with a diameter of 7 nm. Hyperfine measurements also show that the magnetic hyperfine field (Bhf) is 12.6 T at 10 K in the saturated region and the temperature dependence of Bhf indicate that the transition temperature is around 900 K.