The generation of carbon fines by attrition during the fluidized combustion of a bituminous coal has been studied by means of a 140mm ID fluidized‐bed combustor under variable excess air factor, bed temperature, fluidizing velocity and size of bed sand and coal. Results indicate that rates of attrited fines are roughly proportional to excess of gas velocity above the minimum for fluidization and bed carbon exposed surface. Attrition rate constant is affected by size of sand and, to a less extent, and particularly with finer coal, by bed temperature.
ABSTRACT:The water solutions of the block copolymers PEO n -PPO m -PEO n , known as pluronics, show a complex thermal behavior, since they are liquid at low temperature (5 C), and they can give soft gel when heated at body temperature (37 C). These properties are of great interest in biomedical applications. To properly design these applications, a prerequisite is the knowledge of the thermodynamics-how much-and of the kinetics-how fast-with which these transformations take place. In this work, solutions of F127 (the copolymer for which n ¼ 100 and m ¼ 65) were studied by varying the concentration and the temperature and analyzing their behavior when heated under several heating rates. The studies were performed by differential scanning calorimetry (DCS) and dielectric spectroscopy. The investigations carried out under equilibrium conditions allowed us to determine the thermodynamics of the phase transitions, whereas the investigations carried out under varying conditions allowed us to quantify the kinetics of the phase transitions. Empirical models were also proposed to describe both the thermodynamics and the kinetics observed.
Biocompatible polymer blends, such as alginate blends, have a\ud
widespread use in pharmaceutical and medical applications due to their specific\ud
features, such as biodegradation, adhesiveness, and thermo- and pH sensitivity\ud
and that can be obtained from the mixture composition. In this work, the use of\ud
alginate blends was tested in a novel production methodology of therapeutic\ud
dosage forms based on polymeric chain reticulation phenomena induced by\ud
exposure to bivalent ions. Two kinds of sodium alginate were used to obtain gel\ud
films (structured films) in blends with Pluronic F127®. The blends were\ud
considered for applications in gel paving of drug-eluting stents. Sodium alginate\ud
was also used in shell–core particle production (structured particles) to obtain\ud
shell-barrier reducing drug release in the preparative steps (see wash operations).\ud
Both structures, films and particles, were obtained using Cu2+ and Ca2+ ions,\ud
respectively. Film/shell barrier properties were tested in dissolution experiments\ud
using vitamin B12 as an active molecule model. Experimental work demonstrated\ud
that the alginate composition is a crucial point in defining reticulated structures
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