The use of biogenic residues to obtain calcium phosphate compounds, mainly hydroxyapatite (HAp), is an excellent alternative to reduce costs in obtaining biomaterials. The purpose of this study was to obtain hydroxyapatite from fish bones and hen eggshells by alkaline hydrolysis and precipitation, respectively, and compare them to HAp obtained from calcium commercial source based on physical-chemical properties and in vitro assays. The biomaterials obtained were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) method and Fourier Transform Infrared Spectroscopy (FTIR). The XRD results revealed the presence of the main characteristic peaks of single HAp phase and FTIR analysis showed various functional groups, such as PO43-, CO3-2 and OH-, confirming the presence of HAp. SEM observations of the synthesized HAp showed a rod-like and spherical-like morphology. The cell viability and bioactivity of the materials were evaluated by rezasurin reduction and McCoy medium assays, respectively. The biomaterials obtained had no toxic effect and the sample obtained from fish bone was more bioactive when compared to the others. Therefore, the biowastes can be used as an alternative source of calcium in the synthesis of hydroxyapatite with promising properties for application in the biomedical area.

Abstract Our research focuses on studying magnon dynamics in a Morse lattice. We used a Heisenberg Hamiltonian to represent the spins while a Morse formalism governed the lattice deformations. The strength of the spin-spin interaction depended on the distance between neighboring spins, which followed an exponential pattern. We explored various initial conditions for the lattice and spin wave function and observed how they affected the magnon-lattice propagation. Additionally, we analyzed the impact of the parameter that controlled the difference in time scales between spin and lattice deformation propagation. deformations spinspin pattern magnonlattice propagation Additionally

Abstract The nanostructured hydroxyapatite (HAp) was synthesized by precipitation from aqueous phase, using hen’s eggshells and different sucrose concentrations. The XRD results confirmed the formation of HAp, with crystallite size of about 15-22 nm. The SEM and TEM characterization showed morphological changes when increasing the amount of sucrose used, with the tendency to form spheroidal particles. The specific surface area increases from 36 to 93 m2.g-1 as the amount of sucrose used increases. Our results indicated that sucrose can be used as a promising additive/template, easy to obtain at low cost. In addition to contributing to the recycling of this biowaste (eggshells), the synthesized HAp has the potential to be used in bone tissue engineering applications, since the samples were no cytotoxicity to dental pulp stem cells in the in vitro assessment by resazurin assay.

The sulfur related thermochemical water-splitting cycles are an important class of chemical processes considered for hydrogen production. Recently, the magnesium sulfate thermal decomposition has been reported as a potential unit operation in one of these cycles. Therefore, some interest has been observed in the use of catalysts to lower the activation energy of such reactions. In this context, the present manuscript reports the thermodynamics and kinetics modeling results associated with this reaction system in the presence of a Pd catalyst supported over γ-Al2O3. The presence of such species is responsible for shifting the decomposition temperature to lower values in at least 100 °C. It was observed that the magnesium content is still oriented towards MgO formation. The obtained results indicate that the Pd/Al2O3 catalyst could be a good alternative in reducing the thermal decomposition temperature as its presence was responsible for diminishing the process activation energy from 368.2 to 258.8 kJ.mol−1.

Abstract: The vibrational modes with nonzero frequency are localized in harmonic lattice with disordered masses. In our work, we investigated numerically the propagation of vibrational energy in harmonic lattice with long-range correlated disordered masses, which are randomly distributed with power law spectrum S ( k ) ∝ k − α. For α = 0, a standard uncorrelated disordered mass distribution was observed and for α > 0 its distribution exhibits intrinsic long-range correlations. Our procedure was done by the numerical solution of the classical equations for the mass displacement and velocities. Energy flow was investigated after injection of an initial wave-packet with energy E0 and the dynamics of the vibrational energy wave-packet was analyzed. We also investigated the dynamics of a pulse pumped at one side of the lattice. Our calculations suggest that vibrational modes with nonzero frequency propagate within harmonic lattice with correlated disordered masses distribution.

O objetivo deste artigo é demonstrar o quanto os conceitos psicanalíticos contribuíram para o ato transformador que pretende a escola. Para isso, foi feita uma análise exaustiva de diretrizes educacionais do estado de Minas Gerais, dos Parâmetros Curriculares Nacionais, do Ciclo Inicial de Alfabetização e do Conteúdo Básico Comum, com o intuito de averiguar não só os aspectos subjetivos presentes direta ou indiretamente nesses materiais, como encontramos, mas também de observar o que se mantém ou é reformulado de um material a outro, confirmando que os mais recentes se baseiam principalmente nos PCN's, com poucas ressalvas. Analisamos o planejamento pedagógico de uma escola municipal da região e constatamos que a subjetividade, indiretamente presente nas diretrizes, mantém-se naquela realidade. Entretanto, constatamos que, nas diretrizes e no projeto pedagógico, a menção ou consideração que seja da subjetividade do professor no processo de ensino-aprendizagem é escassa ou nula.

In what degree have the psychoanalytic concepts contributed to the transforming act intended by schools is the question approached. Therefore, an exhaustive analysis on the educational guidelines of the State of Minas Gerais, Brazil, including the National Curricular Parameters (NCPs), the Initial Cycle of Literacy and the Common Basic Content was undertaken. The aim was not only to investigate the subjective aspects found direct or indirectly in these materials, a task concluded, but also to observe what is preserved or what is remodeled among the materials, confirming that the most recent ones are mainly based on the NPCs, with few exceptions. The pedagogical planning of a municipal school in the region of Inconfidentes was assessed, confirming that the subjectivity, indirectly present in the guidelines, has been preserved in that particular context. However, it has been ascertained that, in the guidelines and in the pedagogical project, the mention or whatever consideration of the teacher´s subjectivity in the teaching-learning process is scarce or null.