Nano alumina powder can be widely used in the fields of electronics, catalyst supports and high temperature applications. In the present article, a nano Al2O3 powder was synthesized by a simple aqueous sol–gel method using inexpensive AlCl3·6H2O and Al powder as raw materials. It was shown that the gel calcined at 1100 °C resulted in the formation of a crystalline α-Al2O3 nano powder. It had a particle size distribution ranging from 32 to 100 nm after heat treatment at 1200 °C.
Let us consider the problem whether there does exist a finite-time self-similar solution of the backward Nike Free Run Uk Sale
type to the semilinear Keller–Segel system. In the case of parabolic–elliptic type for n⩾3n⩾3 we show that there is no such a solution with a finite mass in the scaling invariant class. On the other hand, in the case of parabolic–parabolic type for n⩾2n⩾2, non-existence of finite-time self-similar solutions is proved in a larger class of a finite mass with some Nike Free Mens Sale
Incineration of solid waste with recovery of energy is practiced in communities serving over 30% of the population of the F.R.G. Although solid waste has an energy content corresponding to only 2% of the total energy demand, in individual cases, up to 9% of the electrical requirements (e.g. Munich) are supplied by waste incineration. The basic problems of energy recovery via incineration are reviewed, and a number of practical suggestions are made for the planning and implementation of such schemes.