Syntheses of calcium phosphate nanoparticles, carried out in systems formed from surfactant, oil and water, have resulted in materials with promising possibilities for application. The calcium phosphate particles were synthesized using two different liquid crystals, formed from RenexTM, cyclohexane and a salts solution. The morphology of the nanoparticles synthesized in the liquid crystals is similar to that of hydroxyapatite particles that form bone mineral, where collagen fibers connect these particles so as to form a composite. Therefore, the synthesis of calcium phosphate nanoparticles in the systems used in this work can advance current understanding of mineralization processes that result in the formation of bone mineral.

Neste trabalho, propriedades de hidratação do íon Al3+ são investigadas por simulações mecânico-estatísticas de Monte Carlo no ensemble NpT a 298,15 K e 1 atm usando um modelo de potencial efetivo de pares íon-água cujos parâmetros foram desenvolvidos por meio de busca empírica no espaço de fase configuracional durante o curso das simulações para reproduzir dados experimentais da estrutura da primeira camada de hidratação. Resultados estruturais obtidos a partir das simulações para números de coordenação e distâncias íon-oxigênio da água, correspondentes às camadas de hidratação primeira e segunda, estão em muito bom acordo com dados experimentais. A entalpia de hidratação predita a partir deste modelo também está em muito bom acordo com resultados experimentais e é bastante similar ao resultado obtido por Wasserman et al. a partir do modelo de íon hidratado. Contribuições de muitos corpos investigadas para um cluster [Al(H2O)6]3+ usando a teoria do funcional de densidade em cálculos mecânico-quânticos de primeiros princípios fornecem suporte à efetividade do potencial de pares íon-água desenvolvido quanto aos efeitos de muitos corpos incorporado nos parâmetros ajustados.

In this work, hydration properties of Al3+ ion are investigated by statistical mechanics Monte Carlo simulations in the NpT ensemble at 298.15 K and 1 atm using an effective ion-water potential model whose parameters were developed through empirical search in configurational energy space during the course of simulations to fitting structural experimental data of the first hydration shell. Computed structural results for coordination numbers and ion-water oxygen distances for both first and second coordination shells are obtained in very good agreement with experimental observations. The hydration enthalpy predicted from this simple model is also in very good agreement with experimental values and it is quite similar to the one obtained by Wasserman et al. from the hydrated ion model. Many-body contributions investigated for an [Al(H2O)6]3+ cluster using the density functional theory in ab initio quantum mechanical calculations provide support to the effectiveness of the ion-water pair potential developed concerning many-body effects of water molecules around the ion incorporated in the fitted parameters.

A study was carried out on the urea geometries using ab initio calculation and Monte Carlo computational simulation of liquids. The ab initio calculated results showed that urea has a non-planar conformation in the gas phase in which the hydrogen atoms are out of the plane formed by the heavy atoms. Free energies associated to the rotation of the amino groups of urea in water were obtained using the Monte Carlo method in which the thermodynamic perturbation theory is implemented. The magnitude of the free energy obtained from this simulation did not permit us to conclude that urea is non-planar in water.

Multicomponent ceramics are mainly synthesized by conventional solid-state reaction route and sol-gel routes. In the sol-gel route, colloidal or polymeric gel are envolved. In this work, some principles of the chemistry of theses routes are discused and it is ilustrated a variety of strategies for obtaining a homogeneous multicomponent precursors.