Synthesis and crystal phase evaluation of hydroxylapatite using the rietveld-maximum entropy method

Bioceramic systems based on hydroxylapatite (HAP) are an important class of bioactive materials that may promote bone regeneration. The aim of this research was to evaluate how the stoichiometry of HAP influences its microstructural properties when diagnosed using the combined Rietveld method and Maximum entropy method (MEM). The Rietveld Method (RM) is recognizably a powerful tool used to obtain structural and microstructural information of polycrystalline samples analyzed by x-ray diffraction. Latterly have combined the RM with the maximum entropy method (MEM), with the goal of improve structural refinement results. The MEM provides high resolution maps of electron density and their analysis leave the accurate localization of atoms inside of unit cell. Like that, cycles Rietveld-MEM allow an excellent structural refinement In this work, a hydroxylapatite sample obtained by emulsion method had its structure refined using one cycle Rietveld-MEM with x-ray diffraction data. The indices obtained in initial refinement was Rwp = 7.50%, Re = 6.56%, S - 1.14% e RB = 1.03%. After MEM refinement and electron densities maps analysis to correction of atomics positions, the news indicators of Rietveld refinement quality was Rwp = 7.35%, Re = 6.56%, S = 1.12% and RB = 0.75%. The excellent result obtained to RB shows the efficiency of MEM as auxiliary in the refinement of structure of hydroxylapatite by RM

Primary rhabdomyosarcoma of the diaphragm: case report and literature review Rabdomiossarcoma primário de diafragma: relato de caso e revisão da literatura

The authors report a case of primary rhabdomyosarcoma of the diaphragm, an extremely rare presentation with only 14 cases reported in the literature. An 18-year-old male presented 2 spontaneous occurrences of pneumothorax. Computed tomography and magnetic resonance showed a tumoral mass on the right diaphragmatic surface, and after biopsy, the diagnosis was compatible with spindle cell rhabdomyosarcoma. Because the visceral pleura was invaded by the tumoral mass, a right pleuropneumonectomy was performed. The patient received adjuvant chemotherapy, and there was no evidence of disease 15 months after the operation. Based on the Intergroup Rhabdomyosarcoma Study Group (IRSG) criteria, which consider the extent of the disease and its surgical resectability, rhabdomyosarcomas can be classified into 4 groups. In clinical group I, which was the classification of our patient, the tumor is localized and completely resectable, which implies a good prognosis. Rhabdomyosarcoma is a rare tumor, and a good outcome may result if it is completely resected.<br>Os autores relatam um caso de rabdomiossarcoma primário de diafragma, uma apresentação extremamente rara, com apenas 14 casos descritos na literatura mundial. D.K., masculino, 18 anos, apresentou 2 episódios de pneumotórax espontâneo. Tomografia computadorizada e ressonância magnética evidenciaram massa em superfície diafragmática direita; após biópsia o diagnóstico foi compatível com rabdomiossarcoma embrionário tipo fusocelular, sendo realizada pleuropneumonectomia direita devido à presença de implante tumoral em pleura visceral. Ele recebeu quimioterapia adjuvante e se encontra livre de doença 15 meses após a cirurgia. Os rabdomiossarcomas podem ser divididos em quatro grupos cirúrgico-patológicos, baseados nos critérios do Intergroup Rhabdomyosarcoma Study Group (IRSG) que levam em consideração a extensão da doença e a decisão cirúrgica; no grupo I (como no caso aqui relatado) os pacientes possuem doença localizada completamente ressecada, apresentando o melhor prognóstico. O rabdomiossarcoma é um tumor raro, podendo ter bom prognóstico quando totalmente ressecado