Hydration Heats of Zeolites For Evaluation of Heat Exchangers

The enthalpy of hydration of purified clinoptilolite from Beli Plast, Bulgaria, and various cation-exchanged types such as Na-, K-, Ca- and Mg-clinoptilolite was determined by the adiabatic water-vapor absorption calorimeter. The hydration enthalpy becomes more exothermic in the sequence K, Na, Ca, Mg depending on hydration energy values of exchanged cations. Na-clinoptilolite would be an efficient heat exchanger in a wide temperature range of dehydration, 180–300°C, while Mg-clinoptilolite in higher temperatures, 300–350°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sur l'histoire des démonstrations analytiques du théorème fondamental de l'algèbre

The first proof of the fundamental theorem of algebra, proposed by D'Alembert in 1746 and practically unknown to this day, stimulated a series of “analytic” proofs which made essential use of the properties of polynomials as analytic functions and placed the theorem within complex analysis. One of the simplest and most widely known modern proofs is formed from the “analytic” proofs of Gauss, Argand, Legendre and Cauchy, which used and developed the ideas of D'Alembert.     

On Macrocrack–Microdefect Interaction

A review is given of studies devoted to problems and methods of evaluating the effective resistance to macrocrack growth in materials with microdamages and in materials reinforced with small rigid inclusions under mechanical and thermal loads. Also an analysis is made of the three-dimensional interaction of penny-shaped microcracks and macrocracks in isotropic and transversely isotropic materials. Related publications based on methods and models other than those used by the authors are reviewed.     

Copolymerization of acetylene with ethylene in the presence of dibenzenetitanium(0)

The interaction between acetylene and dibenzenetitanium(0) at a room temperature results in the acetylene polymerization and its reduction to ethylene, ethane, and methane at the expense of H atoms of the acetylene molecule. The catalytically active species capable of copolymerizing acetylene with ethylene that are formed during the reaction or are added into the system originate from the interaction of dibenzenetitanium(0) with acetylene.