C.C. Silva

Structural properties of hydroxyapatite obtained by mechanosynthesis

In this paper mechanical alloying has been used successfully to produce nanocrystalline powders of hydroxyapatite (HA) using five different experimental procedures in a pure dry process. The milled HA were studied by X-ray powder diffraction, infrared and Raman scattering spectroscopy. For four different procedures, HA was obtained after a couple of hours of milling (in average 60 hours of milling, depending in the reaction procedure). This milling process, used to produce HA, presents the advantage that melting is not necessary and the powder obtained is nanocrystalline with crystallite size in the range of 22 nm to 39 nm.

Piezoelectric properties of collagen-nanocrystalline hydroxyapatite composites

In this paper we did a study of the physicochemical, dielectric and piezoelectric properties of anionic collagen and collagen-hydroxyapatite (HA) composites, considering the development of new biomaterials which have potential applications in support for cellular growth and in systems for bone regeneration. The piezoelectric strain tensor element d14, the elastic constant s55, and the dielectric permittivity ɛ11 were measured for the anionic collagen and collagen-HA films. For the collagen-HA composite film (Col-HACOM) the main peaks associated to the crystalline HA is present. For the nanocrystalline composite, nanometric HA powder (103 nm particle size) (HAN), obtained by mechanical milling were used. For the composite film (Col-HAN) the HA and CaH(PO4)2H2O phases were detected. One can see that the HA powder (HAN) present the main peaks associated to crystalline HA. The IR spectroscopy measurements on HA-COM and HAN powders, Col-HACOM and Col-HAN composite films and collagen film (Col) presents the main resonances associated to the modes of (PO4)3−, (CO3)2−. The IR spectra of Collagen Film (Col) shows the bands associated to amide I (C=O), amide II (N–H) and amide III (C–N) vibrational modes. The scanning electron photomicrography of the Col-HACOM and Col-HAN films, respectively, shows deposits of HA on the surface of collagen. It also shows that HACOM crystals has a dense feature, whereas the HAN crystals has soft porous surface. Energy-dispersive spectroscopy (EDS) analysis showed that the main elements of the hybrid sponge were carbon, oxygen, calcium, and phosphorus. The EDS of HACOM crystal, present in the Col-HACOM composite showed a molar ratio Ca/P = 1.71, whereas the Col-HAN composite the molar ratio of calcium and phosphorus (Ca/P = 2.14) and the amount of carbon were greater. The piezoelectric strain tensor element d14 obtained for the anionic collagen was around 0.102 pC/N. The collagen composite with nanocrystalline HA crystals (Col-HAN) present a better result (d14 = 0.040 pC/N) compared to the composite with the commercial ceramic (d14 = 0.012 pC/N). This is an indication that the nanometric particles of HA present little disturbance on the organization of the collagen fibers in the composite. In this situation the nanometric HA are the best candidates in future applications of these composites.

Centro de informação sobre medicamentos: contribuição para o uso racional de fármacos

Este artigo descreve o primeiro ano de atividades do Centro de Informacao sobre Medicamentos da Universidade Federal do Ceara, em Fortaleza, Brasil. O CIM faz parte do GPUIM (Grupo de Prevencao ao Uso Indevido de Medicamentos, do Departamento de Farmacia), sendo operacionalizado por farmaceuticos especializados. O servico atende a comunidade em geral e aos profissionais da saude em particular. De dezembro de 1994 a novembro de 1995, 246 pessoas telefonaram ao CIM-UFC, das quais 39% eram usuarios de medicamentos, 32% farmaceuticos, 17% parentes e/ou amigos dos usuarios, 4,5% estudantes de Farmacia e/ou de Medicina, 4% medicos, 0,8% enfermeiras e 2,8% outros. Os temas mais abordados foram Reacoes Adversas (28%) Indicacoes (28%) e Eficacia (18%), sendo os grupos de farmacos mais frequentes: Vitaminas, Analgesicos e Agentes Antiinflamatorios. O numero de solicitacoes vem aumentando regularmente, variando com a divulgacao do servico atraves da midia local e de publicacoes especificas. Nesse periodo, o Centro vem esbocando o perfil de um servico que pode preencher lacunas importantes nao so do Sistema de Saude, como tambem da formacao e pratica de medicos e farmaceuticos. Alem disso, o Centro esta se firmando como uma fonte segura de informacoes auxiliares nas decisoes das pessoas leigas no que diz respeito a automedicacao.

Structural studies of calcium phosphate doped with titanium and zirconium obtained by high-energy mechanical alloying

In this paper, we present a new variation of the solid-state procedure on the synthesis of bioceramics with titanium (CapTi) and zirconium (CapZr), considering that zirconium (ZrO2) and titanium oxide (TiO2) are strengthening agents, due to their superb force and fracture toughness. The high efficiency of the calcination process opens a new way of producing commercial amounts of nanocrystalline bioceramics. In this work, a new variation of the solid-state procedure method was used to produce nanocrystalline powders of titanium and zirconium, using two different experimental chemical routes: CapTi: Ca(H2PO4)2+TiO2 and CapZr: Ca(H2PO4)2+ZrO2. The powders were submitted to calcination processes (CapTic and CapZrc) at 800, 900 and 1000 °C. The calcium titanium phosphate phase, CaTi4P6O24, was obtained in the CapTic reaction and the calcium zirconium phosphate, CaZr4P6O24, was obtained in the CapZrc reaction. The obtained ceramics were characterized by x-ray powder diffraction (XRD), infrared (IR) spectroscopy, Raman scattering spectroscopy (RSS) and scanning electron microscopy (SEM) analysis. This method was compared with the milling process (CapTim and CapZrm), where in the last process the melting is not necessary and the powder obtained is nanocrystalline. The calcium titanium phosphate phase, CaTi4P6O24, was obtained in the reaction CapTim, but in CapZrm the formation of any calcium phosphate phase even after 15 h of dry mechanical alloying was not observed.

Magnetic properties study on Fe-doped calcium phosphate

Calcium phosphates are very important for applications in medicine due to their properties such as biocompatibility and bioactivity. In order to enhance these properties, substitution of calcium with other ions has been proposed. Partial substitution of calcium by different ions has been made in order to improve the properties of the calcium phosphates and also to allow new applications of apatite in medicine. In this work, hydroxyapatite [Ca10(PO4)6(OH)2?HAP] was prepared by high-energy dry milling (20?h) and mixed with iron oxide (5?wt.%). The mixture was calcinated at 900??C for 5?h with a heating rate of 3??C?min?1 in an attempt to introduce iron oxide into the HAP structure. The sintered sample was characterized using x-ray diffraction (XRD) and magnetization. The 57Fe-M?ssbauer spectra of the calcium phosphate oxides were also measured, revealing the presence of iron in three different phases: Ca2Fe2O5, Fe2O3 and hydroxyapatite.

Structural study of Fe2O3-doped calcium phosphates obtained by the mechanical milling method

In this study, iron oxide was added with different concentrations (0.5, 1, 2.5 and 5 wt%) of hydroxyapatite (HAP) obtained by the mechanical milling method. The mixture was calcinated at 900 °C for 5 h with a heating rate of 3 °C min−1. The influence of the incorporation of different amounts of iron oxide was investigated by x-ray diffraction using both the Rietveld method and scanning electron microscopy. Calcium phosphates have a wide range of applications, particularly in the biomedical field. HAP stands out in this group of compounds due to its excellent biocompatibility, because it is very similar to the inorganic tissue of the bone matrix, both in chemistry and crystallographic structure. Among the cations that could substitute for calcium in the HAP structure, iron has gained importance recently, because it can form ferrites, which could be used for the treatment of cancer by hyperthermia. Iron could also influence the physiochemical properties of HAP, improving its potential as a biocompatible material.

The Modulus Formalism Used in the Dielectric Analysis with Optical Characterization of Hydroxyapatite and CaTi4P6O24 Ceramic Formers by Dry Ball Milling

The bioceramic hydroxiapatite [Ca10(PO4)6 (OH)2 – HAP] is the main mineral constituent of teeth and bones with excellent biocompatibility with hard and muscle tissues. These materials exhibit several problems of handling and fabrication, which can be overcome by mixing them with a suitable binder. The dry milling process of fabrication of HAP presents the advantage that melting is not necessary and the powder obtained is nanocrystalline. The HAP has been obtained from three different experimental procedures (HAPA: Ca(H2PO4)2 + Ca(OH)2; HAPB: Ca(H2PO4)2 + CaCO3; and HAPC: CaHPO4 + CaCO3). In the reactions HAPA and HAPB the hydroxiapatite phase was obtained after 5, 10 and 15 hours of milling and after 15 hours in the reaction HAPC. In order to improve the mechanical properties of HAP, calcium phosphate ceramics with titanium (CaP-Ti) has been prepared by dry ball milling (Ca(H2PO4)2 + TiO2). The calcium titanium phosphate phase, CaTi4P6O24, was obtained. The dielectric study in function of frequency, at constant temperature of the ceramics, was made using the Modulus (M*) formalism and a distribution of relaxation times was observed. The values of the dielectric constant of the ceramics measured at room temperature are between 5.04 (CaP-Ti_5H) and 13.70 (HAPA_10H). The structure of the samples was studied by X-Ray diffraction, infrared and Raman scattering spectroscopy.

Por uma filosofia do medicamento

Medicine and philosophy: where do these concepts intersect? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.Medicine and philosophy: where do these concepts intersect? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.Medicine and philosophy: where do these concepts intersect ? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.Medicine and philosophy: where do these concepts intersect? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.

Towards a philosophy of medication

Medicine and philosophy: where do these concepts intersect? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.Medicine and philosophy: where do these concepts intersect? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.Medicine and philosophy: where do these concepts intersect ? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.Medicine and philosophy: where do these concepts intersect? From a biopolitical standpoint, the scope of this essay is to highlight the existence of new challenges for those who deal with the issue of pharmaceuticalization in contemporary society. The analyses revealed that essentially technical approaches are insufficient to confront issues such as: the exorbitant profits from the sale of medication; the disproportionate ratio of these amounts with the number of new innovative molecules; and the difficulty of access to the few new drugs. It would seem to be the opportune moment for adopting a more critical stance for drafting a philosophy of medication in the field of public health with the establishment of areas of resistance to the omnipresent pharmacotherapeutic onslaught. After all, medication is not a constitutive element that is isolated from human life; although, it has become a central component in the management of contemporary life, its adequate use requires the exercise of in-depth introspection.