Nowadays, sustainability and good use of resources and waste are necessary. So, this work seeks to synthesize a ceramic material from natural waste, as well as its characterization and biological evaluation after all the steps that anticipate in vivo application. In this way, brushite, which is a dihydrate dicalcium phosphate mineral that is a calcium phosphate present in the natural mineralization of tissues, can be obtained synthetically from chicken eggshells. It is used as a biomaterial for different applications such as medical treatment, especially orthopedic treatment and bone repair, agrobiological inorganic fertilizers. Brushite has the property of adsorbing ions and changing its active sites with calcium, such as Zn and Ag ions, which can enhance the biocompatible and bactericidal potential of the biomaterial, respectively. In this work, we started with the synthesis of bruxite nanopowders (previously performed) that was characterization by microscopy and physical-chemistry analysis (MEV-topography, MET-nanoscale, FTIR-chemistry-group, XRD Rietveld- material identity). The cytotoxicity was then tested by in vitro microbiological analysis in a nutrient medium using 3 species of bacteria was made ISO-10993-5- ceramic tests. The results shows that was possible to obtain bruxite through the results of chemical-physical characterization and the initial results in vitro indicate that it is a biocompatible nanoceramic. 

Thanks to Faperj 203.409/2023 - SEl-260003/016585/2023 for supporting the research, to CAPES, CNPQ and to the student Ronald Palandi Cardoso for helping with the cultivation of microorganisms and to Prof. Yutao Xing for helping with the MET analysis.

It was recently presented a model [1-3] able to predict the magnetic anisotropy of any sample, This is called the "Simultanoeus Fitting Method" SFM.

According the SFM method, the magnetic anisotropy can be determined, since magnetic measurements are performed at the  (_|_) perpendicular and (//) parallel directions (relative to the alignment direction). The method assumes samples with alignment in one preferential direction, thus with uniaxial anisotropy. This kind of anisotropy is typically found in samples prepared by powder metallurgy, where the alignbment is obtained by applying magnetic fields in grains with single domain size. 

Using the SFM, the crystallographic texture of samples can be determined directly from magnetic measurements, avoiding complicated, laborious and expensive techniques as EBSD - Electron BackSacterred Diffraction.

A symmetrical distribution as for example the Gaussian, is used for describing the crystallographic texture.

Other distribution functions can also be used, since they are symmetrical. This includes Cauchy -Lorentz, Voigt and Pearson VII as possibilities.

It is experimentally found that f=cos(theta)^n or Gaussian distributions describe very well the texture of the samples.

The model allows the re-evaluation of experimental data. Here it is discussed how to apply the model in very different samples.

These samples are SmFeN (magnetocrystalline anisotropy), Alnico, (shape anisotropy [4,5]) and cobalt-needle samples.

In cobalt needle samples the shape anisotropy and the magnetocrystalline anisotropy may have the same order of magnitude.

It is discussed the question of dominant anisotropy.

The hysteresis curves of a material are capable of showing the relationship between the magnetization and the applied magnetic field. These curves are crucial to understanding the magnetic properties of ferrites, which are widely used in electronic applications, such as transformers and inductors. In this work, hysteresis curves of barium and strontium ferrites, in varying proportions, were adjusted using the Hyperbolic Tangent Model. This model demonstrated a good capacity for adjusting the observed hysteresis curves, which present a characteristic sigmoidal aspect. The parameters obtained from the adjustment allowed a better understanding of the physical and magnetic properties of the analyzed samples. The Hyperbolic Tangent Model proved to be effective not only due to the high correlation coefficient achieved, but also due to its ability to reflect the nuances of the magnetic properties under different conditions. The results obtained may have significant implications for the application of these ferrites in magnetic and electronic devices, since understanding their fundamental properties is crucial to optimizing the performance of these materials in different contexts. In short, the work highlights the importance of mathematical modeling as a tool for elucidating the magnetic characteristics of barium and strontium ferrites. The results suggest that the Hyperbolic Tangent Model is a promising approach for future investigations into magnetic materials consisting of ferrites.