Investigations on the crystallization of larger NaA and NaX zeolite crystals in the presence of triethanolamine (I). The influence of Na2O and SiO2 content

Sodium silicate-aluminate aqueous systems with various contents of Na₂O and SiO₂ containing triethanolamine were crystallized. Optimum Na₂O and SiO₂ contents have been observed to give NaA and NaX zeolite crystals with dimensions up to 80 μm. For NaA crystals the values are: ∼ 3.5 mass% Na₂O, ∼ 1.65 mass% SiO₂; for NaX crystals ∼ 2.5 mass% Na₂O, ∼ 1.5 mass% SiO₂. – The effect of other additives on crystal size is proved. – The results are discussed in terms of nucleation and growth, reaction rate, and supersaturation. Supposition are made to gain larger crystals by maintaining the excess of solute over a longer period of time.     

The active centres' nature in anionic polymerization of polar monomers

In the anionic polymerization of polar monomers the nature of active centres is considerably influenced by the reaction conditions. In a survey, the present state of knowledge is represented and discussed for the polymerization of acrylonitrile. Analogous problems of methyl methacrylate and vinylpyridine polymerization are included in the considerations.     

Element specific surface reconstructions of islands during surfactant-mediated growth on Si (111)

The early stages of surfactant- (As, Sb) mediated homoepitaxial growth on Si (111) are examined by scanning tunneling microscopy and extensive ab initio calculations of Si(n) clusters (n相似文献   

Optimal Co-Operative Advertising Decisions in Direct-Mail Operations

This paper considers optimization of vertical co-operative promotion decisions in a direct mail operation. After presenting our model, we demonstrate that it is likely that a vertical co-operative direct mail promotional effort can result in a situation in which both the direct mailer and the manufacturer increase profits, compared with the situation where the direct mailer makes ‘optimal’ direct mail decisions without regard to any involvement with the manufacturer. We next show that the manufacturer can optimize his own profitability by agreeing to a specific (quantitatively determined) contribution to mail order costs. Finally, we illustrate how the manufacturer and direct mailer can co-operate (move away from their individual optimal decision variables), reaching an integrative, rather than a distributive solution, and jointly set the values of these decision variables, so that the total profit generated by the operation is higher than the sum of the individual profits of the two parties.