The CeCl3·7H2O-NaI system as promoter in the synthesis of functionalized trisubstituted alkenes via Knoevenagel condensation

The arylidene malonates with two different geminal carboxylate functions, a suitable class of substrates of several synthetic and pharmacological studies, are easily available through Knoevenagel condensation of ethyl tert-butyl malonate and different aromatic aldehydes. The results have increased the potentialities of CeCl₃·7H₂O-NaI system as a type of water-tolerant green Lewis acid promoter for carbon-carbon bond forming procedures.     

The Cauchy-Goursat problem for wave equations with nonlinear dissipative term

The Cauchy-Goursat problem for wave equations with nonlinear dissipative term is studied. The existence, uniqueness, and blow-up of global solutions of this problem are considered. The local solvability of this problem is also discussed.     

The first Darboux problem for wave equations with nonlinear dissipative term

The first Darboux problem for wave equations with nonlinear dissipative term is considered. The uniqueness, local and global existence and blow-up of solutions of the problem mentioned are investigated. The paper’s originality is the coalescence of two standard methods: a priori estimate of solutions in the class of continuous functions is given by energetic methods; basing on this result a priori estimate in the class of continuously differentiable functions using classical method of characteristics is obtained.     

Amino Acid Based Epoxy-Poly(Ester Amide)s—A New Class of Functional Biodegradable Polymers: Synthesis and Chemical Transformations

A new class of biodegradable functional polymers – epoxy-poly(ester amide)s (EPEAs), was synthesized for the first time on the basis of naturally occurring α-amino acids, fatty diols and cis- and trans-epoxysuccinic acids. The syntheses were conducted via both solution Active Polycondensation and Interfacial Polycondensation using, accordingly, either activated di-p-nitrophenyl esters or dichlorides of cis- and trans-epoxysuccinic acids as bis-electrophilic monomers. Di-p-toluenesulfonic acid salts of bis-(L-phenylalanine)-1,6-hexylene and bis-(L-leucine)-1,6-hexylene diesters were used in both cases as bis-nucleophilic counter-partners. High-molecular-weight polymers (M_w up to 67.000) with desirable material properties were obtained via solution polycondensation using di-p-nitrophenyl-trans-epoxy succinate. The EPEAs were chemically modified further under mild conditions: oxirane groups along the backbone were reacted with both nucleophilic and electrophilic reagents, and also subjected to thermal and chemical curing. The macromolecular transformations of EPEAs substantially broaden material properties and, hence, the potential to apply amino acid-based biodegradable poly(ester amide)s as absorbable drug carriers and surgical devices.     

U-Closure Operators and Compactness

A notion of compactness with respect to a previously introduced notion of functor induced closure operator is presented and analyzed. Even though this new notion shows very similar properties to compactness with respect to the classical notion of categorical closure operator, in general the two concepts are different. Examples are provided.     

The efficient use of vehicles with pneumatic suspensions in bad road conditions

Air dampers for pneumatic suspensions are considered. Results of investigations and methods for calculation of characteristics and design parameters are presented.     

Experimental results on quadratic maps using generalized complex numbers

Summary Some results obtained introducing two-unit generalized complex numbers to determine Mandelbrot and Julia sets for quadratic maps are presented. We also highlight some analogies and differences between classic complex numbers and one of the proposed extensions. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Capanello, Italy, July 4–8, 1994.     

On the Solvability of a Mixed Problem for an One-dimensional Semilinear Wave Equation with a Nonlinear Boundary Condition

In this paper, for an one-dimensional semilinear wave equation we study a mixed problem with a nonlinear boundary condition. The questions of uniqueness and existence of global and blow-up solutions of this problem are investigated, depending on the nonlinearity nature appearing both in the equation and in the boundary condition.     

On Equivalent Equilibrium Problems

We give sufficient conditions for the equivalence between two equilibrium problems. In particular we deduce that, under suitable assumptions, an equilibrium problem has an equivalent reformulation as a generalized variational inequality. Such conditions are satisfied when the equilibrium bifunction is lower semicontinuous, coercive and quasiconvex with respect to the second variable. We also show that the equivalent generalized variational inequality inherits the same generalized monotonicity properties of the original nonconvex equilibrium problem.