Azathioprine is an immunosuppressive drug for several inflammatory disorders. Due to its clinical relevance, to explore the solid-state properties for excipient compatibility in the product quality review process is essential. Fourier transform infrared spectroscopy, powder X-ray diffraction and thermal analysis (thermogravimetry/derivative thermogravimetry (TG/DTG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC)) were applied. The compatibility studies evidenced that starch pregelatinized, colloidal silicon dioxide, and talc are fully compatible with azathioprine. However, stearic acid, magnesium stearate, and mannitol are incompatible after heat supply at temperatures easily reached by industrial processing. The nonlinear Vyazovkin isoconversional treatment performed the kinetic study of the thermal degradation. The activation energies were determined to clarify the influence of each excipient on the thermal drug stability, an essential procedure in the pharmaceutical development, and all over the commercial live span, in Good Manufacturing Practices.

Much is said and written regarding alchemy all across the world, in what could be called a renaissance of alchemical studies. However, relatively little is done in terms of actual alchemical laboratory work. The aim of the project described herein was to show how crucial the development of technical alchemical practice was along the centuries, in the discovery of an immense number of substances, processes and operations, which were of paramount importance in the establishment of modern chemistry. Alchemy is often derided in many circles. On the contrary, for two thousand years it constituted the basis of humankind’s understanding of the material world and the changes undergone by compounds and materials. Here we present an experimental reconstitution of several alchemical discoveries of great importance, using old descriptions followed by modern characterizations. The results were often startling and demonstrated how ancient wisdom bore fruit in different ways, even in the absence of our present-day means of analysis.

Thermal analysis can be used to determine shelf-life and kinetic parameters in pharmaceutical systems. This work investigates the kinetic of lumefantrine thermal decomposition, an antimalarial, using non-isothermal and isothermal experimental data. The non-isothermal conditions are analyzed applying Vyazovkin method, while isothermal conditions employ models fitting procedure and artificial neural network. Lumefantrine was characterized by powder X-ray diffraction and Fourier transform infrared spectroscopy. The initial stage of lumefantrine thermal decomposition, about 5% of conversion, corresponds to the loss of chlorine and hydroxyl, being correctly predicted by the neural network as a complex event. At room temperature, the D3 model is appropriate to describe the process, once the half-life time is 19 months, in agreement with manufacturer. Isoconversional model determined the activation energy along the whole process while isothermal methodology determined the global value considering the entire process. The results provide important information for the pharmaceutical industry to assay levels of acceptable lumefantrine contents.

Although largely used in mobiles and electric vehicles applications, insertion batteries based on Li-ion technology are high-cost devices. These applications require high-performance energy storage systems with high-energy and high-power densities, which are better attained by Li-ion technology. However, stationary applications such as power plants and uninterruptible power supplies (UPS) mainly require low-cost energy storage devices. In this scenario Na-ion insertion batteries feature as a cheaper option for such applications. Among the several compounds for use as cathode in Na-batteries, a largely studied class of compounds are the sodium-carbonate-phosphates, Na3MCO3PO4 (M = Mn, Fe, Co or Ni), with structure analogue to the mineral sidorenkite. In this work, it was developed a new microwave-assisted hydrothermal method as an ultra-fast way to prepare sodium-carbonate-phosphate compounds. This methodology results in high-quality materials with general formula Na3MCO3PO4 (M = Mn, Fe, Co or Ni) upon only 5 min processing time. Characterization techniques indicate highly ordered materials with sidorenkite-like phase and different morphologies or crystal habits, including plates, rods, and a ‘starfruit’ shape. As a proof-of-application the Mn-based material was evaluated from electrochemical tests for Na+ insertion reactions. The obtained results evidence initial discharge capacity of 107 mA h g-1 with good reversible capacity (65 mA h g-1) after several charge/discharge cycles.

Lamivudina e efavirenz estão entre os fármacos mais utilizados em todo o mundo para o tratamento da síndrome da imunodeficiência adquirida (AIDS). Foram utilizadas as técnicas de ressonância magnética nuclear de estado sólido (ssNMR), espectroscopia no infravermelho por transformada de Fourier (FTIR), calorimetria exploratória diferencial (DSC), e análise termo-óptica (TOA) para estudar possíveis interações entre esses fármacos, visando o desenvolvimento de uma combinação em dose fixa dos mesmos. DSC e TOA evidenciaram deslocamentos significantes das temperaturas de fusão dos fármacos na mistura, o que sugere uma interação entre eles. Apesar de os resultados de DSC e TOA indicarem incompatibilidade entre as drogas, os espectros de FTIR não apresentaram modificações devido à sobreposição de bandas. As análises de ssNMR mostraram mudanças significativas nos valores de deslocamento químico da mistura quando comparados aos dos fármacos puros, especialmente nos sinais referentes a átomos de carbono deficientes em elétrons. Essses resultados confirmam as interações sugeridas pelo DSC e TOA, devido provavelmente a interações ácido-base entre átomos eletronegativos e deficientes em elétrons dos fármacos.

Lamivudine and efavirenz are among the most worldwide used drugs for acquired immune deficiency syndrome (AIDS) treatment. Solid state nuclear magnetic resonance (ssNMR), Fourier-transformed infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermo-optical analysis (TOA) were used to study possible interactions between these drugs, aiming the development of a fixed-dose drug combination. DSC and TOA have evidenced significant shifts on the melting points of both drugs in the mixture, which may be due to interaction between them. Although DSC and TOA results indicated incompatibility between the drugs, FTIR spectra were mostly unmodified due to overlapping peaks. The ssNMR analyses showed significant changes in chemical shifts values of the mixture when compared with spectra of pure drugs, especially in the signals relating to the deficient electron carbon atoms of both drugs. These results confirm the interactions suggested by DSC and TOA, which is probably due to acid-base interactions between electronegative and deficient electron atoms of both lamivudine and efavirenz.

Three samples of hydrotalcite-like materials (HTC) were synthesized and their structural characteristics were compared with two HTCs obtained commercially. Thermal analyses, FT-IR, PXRD and textural analyses were used to investigate the structural differences between commercial and synthetic samples. Particularly, the memory effect was observed at temperature higher than 600 ºC. The Rietveld refinements were obtained with expressive accuracy and the statistical parameters of goodness of fit are quite satisfactory. In conclusion, the procedures adopted in synthesis of HTC produced crystalline materials with high surface area materials.

Frações magnéticas de duas amostras coletadas a 5 m e 52 m de profundidade, a partir do topo de um manto de intemperismo desenvolvido sobre periodito, da área de mineração de níquel em Cerro Matoso (7° 54' 31" N 75° 33' 23" O), Departamento de Córdoba, Colômbia, contêm minerais magnéticos e não magnéticos, intimamente associados. Frações magnéticas, posteriormente concentradas por tratamentos químicos seletivos com NaOH 5 mol L-1, para remover silicatos, e com uma mistura citrato - bicarbonato - ditionito (CBD), para remover óxidos de ferro não magnéticos, foram analisadas por difratometria de raios X, espectroscopia Mössbauer à temperatura do ambiente, magnetização de saturação, microscopias ótica e eletrônica por varredura e espectroscopia de energia dispersa, para se obter uma descrição detalhada das fases magnéticas presentes. Os tratamentos químicos foram efetivos na concentração dos óxidos de ferro, de tal sorte a permitir melhores resultados da análise mineralógica do minério de níquel. Os resultados Mössbauer revelaram que o tratamento com NaOH removeu silicatos e cromita e que a mistura CBD solubilizou seletivamente hematita, goethita e magnetita não estequiométrica, parcialmente oxidada.

Two magnetic samples, collected at 5 m and 52 m from the top of a weathering mantle developing on peridotite, from the Cerro Matoso (7° 54' 31" N 75° 33' 23" W) mining area for nickel, Department of Cordoba, Colombia, were submitted to magnetic separation with a hand magnet in the laboratory. The so concentrated samples were found to contain intimately associated magnetic and non-magnetic minerals. The magnetic phases were further concentrated by selective chemical treatments with 5 mol L-1 NaOH to remove silicates, and with a mixture citrate - bicarbonate - dithionite, to remove non-magnetic iron oxides. Powder X-ray diffractometry, RT Mössbauer spectroscopy, saturation magnetization measurements, scanning electron microscopy, energy dispersive spectroscopy and optical microscopy analyses were used to give a mineralogical description of the magnetic phases. The chemical treatments were effective on concentrating iron oxides so to improve the mineralogical analysis of this nickel ore. Mössbauer analysis revealed that NaOH selectively removed silicates and chromite from samples, whereas CBD dissolved hematite, goethite, and partially oxidized non-stoichiometric magnetite.