Intramolecular Hydrogen Bond and Internal Rotation of Aminogroup in Esters of Aminoacrylic Acids

The NMR ¹H and IR spectra of ethyl esters of two β-alkyl and β-aryl substituted of β-aminoacrylic acid have been measured. The results are evidence of the strong intramolecular hydrogen bond between amino group and carbonyl oxygen. The activation energy of about 20 kcal/mol was obtained for the internal rotation around C-N bond.     

Local parameter identifiability for one class of hybrid systems

We consider the problem of local parameter identifiability for a hybrid system with components that are continuous and discrete in time. The set of observations is the vector-solution (depending on the parameter that is continuous in time) of the discrete component. Sufficient conditions of local parameter identifiability have been formulated using the earlier introduced notion of normalized separability of the set of parameters from the kernel of a special functional. An example where the condition of normed separability is reduced to some rank criterion is given.     

Prevalence of locally parameter identifiable systems

The problem of local parameter identifiability of an input–output system is considered. A set lf of systems is studied for which the property of local parameter identifiability holds for almost all values of input signals and parameters in both topological and metric senses. Sufficient conditions are pointed out under which the set LI contains a prevalent subset. The proof is based on the prevalent transversality theorem proved by Kaloshin. Systems are considered that are characterized by a family of (structural) parameters a and a control block. It is shown that if the dimension of the set of parameters a is large enough (the structure of the system is rich enough), then, generically, a system f _a belongs to the class lf for a set of parameters a having full measure.     

Effect of solvent nature on the optical anisotropy of poly(1-trimethylsilyl-1-propyne) molecules

The optical properties of poly(1-trimethylsilyl-1-propyne) solutions in solvents possessing optical anisotropy have been studied with dynamic birefringence measurements. In solvents characterized by refractive indexes different from the refractive index of a dry polymer, the optical form effect has been discovered. This effect is determined by the shape asymmetry of a macromolecular segment and its rigidity. Estimates showed that the length of the statistical segment, which characterizes the thermodynamic rigidity of the macromolecular chains under study, is 82 × 10^?8 cm. The shear optical coefficient for solutions of the test polymer in an anisotropic solvent is markedly higher than the corresponding value in an isotropic solvent. This difference is related to the orientation of anisotropic solvent molecules along the main chain of a macromolecule by their highest polarizability axis. Under the assumption that the orientational order of solvent molecules relative to chain macromolecules is independent of the thermodynamic rigidity of chain molecules, the size of the statistical segment of the macromolecules in question has been independently estimated as 98 × 10^?8 cm.     

Optical anisotropy of molecules of pyromellite-dianilic amido acid polyesters

The optical anisotropy of molecules of pyromellite-dianilic amido acid polyesters has been studied by the method of flow birefringence. Positive flow birefringence, which depends on the isomeric composition of the repeating unit, is detected. The thermodynamic rigidity of pyromellite-dianilic amido acid polyester molecules is calculated in terms of the valence-optical scheme. On passage from 100% para isomers of pyromellite-dianilic amido acid polyesters to macromolecules with a predominant content of meta isomers, optical anisotropy and equilibrium rigidity decrease by a factor of ～2.