Valorization of sugarcane bagasse ash: Producing glass-ceramic materials

Some aluminosilicates, for example mullite and wollastonite, are very important in the ceramic and construction industries. The most significant glass-ceramic for building applications has wollastonite as the main crystal phase. In this work we report on the use of sugarcane bagasse ash (SCBA) to produce glass-ceramics with silicates as the major crystalline phases. The glasses (frits) were prepared by mixing ash, limestone (calcium and magnesium carbonates) and potassium carbonate as the fluxing agent. X-ray fluorescence was used to determine the chemical composition of the glasses and their crystallization was assessed by using thermal analysis (DTA/DSC/TGA) and X-ray diffraction. The results showed that glass-ceramic material can be produced with wollastonite as the major phase, at a temperature lower than 900 °C.We are grateful to PROPE/UNESP/SANTANDER for the post-doctoral scholarship awarded to Dr. Teixeira, to FAPESP (2008/04368-4) for financial support of this project and also to FUNDUNESP for financial aid.Peer reviewe

Nucleation kinetics of crystalline phases from a kaolinitic body used in the processing of red ceramics

The crystallization kinetics of red ceramic raw material from the western part of São Paulo State, Brazil, was examined by differential thermal analysis (DTA) and X-ray diffraction (XRD). The chemical composition of the clay sample was determined by X-ray fluorescence (XRF). Non-isothermal crystallization kinetic methods have been applied to the study of the mechanism of crystallization in this kaolinitic material. The exothermic peak shifted to higher temperatures (945 to 974 °C) with increasing heating rate (10 to 50 °C/min). The average activation energies determined by the Kissinger method (787 ± 85 kJ/mol) and the Ligero method (721 ± 32 kJ/mol) are in agreement. The Avrami constant n obtained by the Ligero method and the m parameter (Matusita method) values were between 1 and 1.5, which indicate a three-dimensional crystal growth with polyhedral morphology and surface nucleation as the dominant mechanism. X-ray diffraction data indicate that this activation energy is not associated with the crystallization of mullite. Scanning electron microscopy (SEM) images of fired (1000 and 1190 °C) samples show their densification during the sinterization process.The authors thank FUNDUNESP and FAPESP (2008/04368-4) for financial support of this work. We also are grateful to PROPE/UNESP/SANTANDER for Dr. Teixeira's post-doc scholarship in MadridPeer reviewe

Risk sharing arrangements for pharmaceuticals: potential considerations and recommendations for European payers

<p>Abstract</p> <p>Background</p> <p>There has been an increase in 'risk sharing' schemes for pharmaceuticals between healthcare institutions and pharmaceutical companies in Europe in recent years as an additional approach to provide continued comprehensive and equitable healthcare. There is though confusion surrounding the terminology as well as concerns with existing schemes.</p> <p>Methods</p> <p>Aliterature review was undertaken to identify existing schemes supplemented with additional internal documents or web-based references known to the authors. This was combined with the extensive knowledge of health authority personnel from 14 different countries and locations involved with these schemes.</p> <p>Results and discussion</p> <p>A large number of 'risk sharing' schemes with pharmaceuticals are in existence incorporating both financial-based models and performance-based/outcomes-based models. In view of this, a new logical definition is proposed. This is "<it>risk sharing' schemes should be considered as agreements concluded by payers and pharmaceutical companies to diminish the impact on payers' budgets for new and existing schemes brought about by uncertainty and/or the need to work within finite budgets</it>". There are a number of concerns with existing schemes. These include potentially high administration costs, lack of transparency, conflicts of interest, and whether health authorities will end up funding an appreciable proportion of a new drug's development costs. In addition, there is a paucity of published evaluations of existing schemes with pharmaceuticals.</p> <p>Conclusion</p> <p>We believe there are only a limited number of situations where 'risk sharing' schemes should be considered as well as factors that should be considered by payers in advance of implementation. This includes their objective, appropriateness, the availability of competent staff to fully evaluate proposed schemes as well as access to IT support. This also includes whether systematic evaluations have been built into proposed schemes.</p