Three-dimensional plotted hydroxyapatite scaffolds with predefined architecture: comparison of stabilization by alginate cross-linking versus sintering

Scaffolds for bone tissue engineering are essentially characterized by porous three-dimensional structures with interconnected pores to facilitate the exchange of nutrients and removal of waste products from cells, thereby promoting cell proliferation in such engineered scaffolds. Although hydroxyapatite is widely being considered for bone tissue engineering applications due to its occurrence in the natural extracellular matrix of this tissue, limited reports are available on additive manufacturing of hydroxyapatite-based materials. In this perspective, hydroxyapatite-based three-dimensional porous scaffolds with two different binders (maltodextrin and sodium alginate) were fabricated using the extrusion method of three-dimensional plotting and the results were compared in reference to the structural properties of scaffolds processed via chemical stabilization and sintering routes, respectively. With the optimal processing conditions regarding to pH and viscosity of binder-loaded hydroxyapatite pastes, scaffolds with parallelepiped porous architecture having up to 74% porosity were fabricated. Interestingly, sintering of the as-plotted hydroxyapatite-sodium alginate (cross-linked with CaCl2 solution) scaffolds led to the formation of chlorapatite (Ca9.54P5.98O23.8Cl1.60(OH)(2.74)). Both the sintered scaffolds displayed progressive deformation and delayed fracture under compressive loading, with hydroxyapatite-alginate scaffolds exhibiting a higher compressive strength (9.5 +/- 0.5MPa) than hydroxyapatite-maltodextrin scaffolds (7.0 +/- 0.6MPa). The difference in properties is explained in terms of the phase assemblage and microstructure.

Stabilization of a Tetrahedral (Mn5+O4) Chromophore in Ternary Barium Oxides as a Strategy toward Development of New Turquoise/Green-Colored Pigments

An experimental investigation of the stabilization of the turquoise-colored chrornophore (Mn5+O4) in various oxide hosts, viz., A(3)(VO4)(2) (A = Ba, Sr, Ca), YVO4, and Ba2MO4 (M = Ti, Si), has been carried out. The results reveal that substitution of Mn5+O4 occurs in Ba-3(VO4)(2) forming the entire solid solution series Ba-3(V1-x MnxO4)(2) (0 < x <= 1.0), while with the corresponding strontium derivative, only up to about 10% of Mn5+O4 substitution is possible. Ca-3(VO4)(2) and YVO4 do not stabilize Mn5+O4 at all. With Ba2MO4 (M = Ti, Si), we could prepare only partially substituted materials, Ba2M1-xMn5+O4+x/2 for x up to 0.15, that are turquoise-colored. We rationalize the results that a large stabilization of the O 2p-valence band states occurs in the presence of the electropositive barium that renders the Mn5+ oxidation state accessible in oxoanion compounds containing PO43-, VO43-, etc. By way of proof-of-concept, we synthesized new turquoise-colored Mn5+O4 materials, Ba-5(BO3)(MnO4)(2)Cl and Ba-5(BO3)(PO4)(MnO4)Cl, based on the apatite-Ba-5(PO4)(3)Cl-structure.

Relation between Stabilization Energy, Crystal Field Coefficient and the Magnetic Exchange Interaction for Tb3+ Ion

Based on a single ion model, Hamiltonian of the simplest form about magnetocrystalline anisotropy for Tb3+ ion was solved by using the numerical method. The relation between the stabilization energy, crystal field coefficient B-2(0) and the magnetic exchange interaction was studied as temperature approaches to 0 K. The results show that the stabilization energy contributed by Tb3+ is linear with crystal field coefficient B-2(0) approximately, but it is insensitive to the change of magnetic exchange interaction for the strong magnetic substances such as TbCo5, Tb2Co17 and Tb2Fe14B compounds.

Projeto de Lei do Plano Nacional de Educação (PNE-2011/2020) : Projeto em tramitação no Congresso Nacional - PL nº 8.035/2010

Apresenta o Projeto de Lei 8530/10 de autoria do Poder Executivo, que institui o Plano Nacional de Educação (PNE).

O legislativo e a sociedade construindo juntos o novo Plano Nacional de Educação

Reúne a legislação pertinente para o debate sobre o novo Plano Nacional de Educação (PNE) que estará em vigor no período de 2011 a 2020: Portaria CNE/CP de 2009 e a Lei nº 10.172/2001.

Plano do carvão nacional : projeto nº 1.045/51

Registra a tramitação do Plano do Carvão Nacional, na Câmara dos Deputados e no Senado Federal, de 24 de agosto de 1951 a 25 de novembro de 1952. Inclui as sessões, atas de reuniões, relatórios, pareceres, emendas. Reúne debates de plenário e comissões, pareceres, vetos, discursos, atas de reuniões e outros documentos parlamentares, mensagens presidenciais, etc.

Plano de valorização econômica do Vale do São Francisco

Registra, em ordem cronológica, a tramitação dos trabalhos na Assembléia Constituinte, nas comissões especializadas e no plenário das duas Casas do Congresso Nacional, até a reunião conjunta destinada ao conhecimento do veto presidencial. Reúne debates de plenários e comissões, vetos, discursos, atas de reuniões e outros documentos parlamentares.

Análise comparativa dos impactos tributários do novo Estatuto Nacional da Microempresa e da Empresa de Pequeno Porte no plano federal

Compara, no que se refere aos tributos federais, o Simples Nacional - sistema tributário introduzido pela Lei Complementar n. 123, de 14 de dezembro de 2006, com o extinto Simples Federal, regulado pela Lei n. 9.317, de 5 de dezembro de 1996, bem como com o lucro presumido, tendo em vista que essas eram as duas formas de tributação mais comumente utilizadas pelos contribuintes que atualmente podem optar pelo Simples Nacional.

Plano Nacional de Recursos Hídricos

Consultoria Legislativa - Área XI - Meio Ambiente e Direito Ambiental,Organização Territorial, Desenvolvimento Urbano e Regional.

Educação à distância, tecnologias educacionais e o Plano Nacional de Educação : elementos para uma avaliação das metas

Consultoria Legislativa - Área XV - Educação, Cultura, Desporto, Ciência e Tecnologia.

Plano Nacional de Educação - um olhar sobre o cumprimento das metas da educação de jovens e adultos

Consultoria Legislativa - Área XV - Educação, Cultura, Desporto, Ciência e Tecnologia.

Coflow jets with large velocity difference - a new aerodynamic principle of flame stabilization and combustion intensification

A new aerodynamic principle of flame stabilization and combustion intensification, the coflow jets with large velocity difference, is described. One or more small high-velocity jets of air or steam, injected off the axis and in the same direction as the low-velocity main fuel-air flow into the combustor, create a large recirculation zone of high turbulence intensity in which the combustibles and high temperature gases are effectively mixed, so that stable and intensive combustion can be maintained even for fuels with poor ignition. A pulverized coal combustor based on the principle mentioned above is shown to be characteristic of excellent combustoom and a simple structure. A number of precombustors of this type are in operation at some power stations and industrial boilers of China. Using such precombustor, successtul startups and part-load operation of the boilers have become available under conditions of unpreheated air and low-grade coal with volatiles as low as 15% and ash content as high as 30%. This principle shows good promise as an attractive new technology of combustion.