Mössbauer research of magnetic particles in medicinal ointments

Stability of the properties of magnetite particles in novel medicinal magnetic ointments of multipurpose application was studied using Mössbauer spectroscopy. Comparative analysis of the results obtained by model fitting of⁵⁷Fe nuclei spectra with those known for the system Fe₃O₄-γ-Fe₂O₃ allowed to identify the phase composition of the particles. This composition, as well as that of the initial pure component in the form of a highly dispersed fraction (～100 Å), differs noticeably from the stoichiometric one. Despite their small sizes, the particles exhibit no superparamagnetism (in the temperature range from 95 to 300 K). Radiative sterilization of the ointments has no effect on the magnetic component composition.     

Study of damage in plastics by optical methods

Conclusion Inclined exposure to radiation, coupled with measurement of the intensity of light fluxes transmitted in the forward direction and reflected from crazes and subsequent interpretation of the results of the measurements using a model that assumes one-time reflection and the presence of a certain functional dependence of the refractive index of the craze along its length, is the most effective of the optical methods that we examined for the investigation of the damage sustained by transparent polymers prone to craze formation. Based on a series of similar analyses, it is possible to evaluate the variation in such craze parameters as total length, form, and degree of loosening in the fatigue process.Translated from Mekhanika Kompozitnykh Materialov, No. 6, pp. 1081–1090, November–December, 1991.     

Calix[4]resorcinolarenes with Thioamide Groups at the Upper Rim of the Molecule

Russian Journal of General Chemistry -     

Spectral analysis of operator polynomials and higher-order difference operators

The study of the spectral properties of operator polynomials is reduced to the study of the spectral properties of the operator specified by the operator matrix. The results obtained are applied to higher-order difference operators. Conditions for their invertibility and for them to be Fredholm, as well as the asymptotic representation for bounded solutions of homogeneous difference equations are obtained.     

The influence of discontinuities in elements of a regular packing on their hydraulic resistance

Russian Journal of Applied Chemistry - Results of testing of hydraulic resistance of a regular packing made from vertical corrugated plates are presented. Experiments were carried out in the range...     

Synthetic transformations of higher terpenoids: XXV. Cross coupling of phlomisoic acid methyl ester with alkenes in the presence of oxidants

The reaction of phlomisoic acid methyl ester with styrene, catalyzed by Pd(OAc)₂, in the presence of Cu(OAc)₂ and 1,4-benzoquinone in a mixture of propionic acid with diethyl ether gave the corresponding 15,16-distyryl derivative and only traces of 15- and 16-monosubstituted furanolabdanoids. Oxidative coupling of the title compound with methyl acrylate under analogous conditions afforded a mixture of 15-mono-, 16-mono-, and 15,16-dialkenylation products whose ratio changed during the process. The reaction was stereoselective, and the exocyclic double bond in the products had exclusively E configuration.     

A gradient method for design of multiorder varied-depth binary diffraction gratings

A method for the design of perfectly conducting varied-depth binary diffraction gratings is proposed. The design uses the rigorous modal expansion method and is based on the gradient search algorithm for optimization of grating structure from the condition of the generation of a desired array of diffraction orders. The designs of varied-depth binary gratings with equal order intensities are reported with an efficiency of more than 90% and root-mean square errors of 2–7%.     

Contact heat transfer between dissimilar materials

The exact solution of the thermoelasticity problem obtained by the authors for a cylinder, one of whose end surfaces is heated while the other is cooled, is used for the first time to quantitatively describe the influence of the magnitude and direction of the heat flux on the contact thermal resistance. It is shown that appreciable macrowaviness of the original flat contacting surfaces can appear as a result of thermal expansion of the contacting samples when heat flows through the contact. Reversing the direction of the heat flux causes changes in the shape of the macrowaviness and in the contact thermal resistance. Zh. Tekh. Fiz. 67, 1–6 (February 1997)     

Robust stability of a class of neural networks with time delays

A stability analysis of the equilibrium position for a given class of Hopfield neural networks with time delays is presented. The robustness of the equilibrium stability with respect to variations in the time delays, system parameters, and interconnection matrix is analyzed. Three approaches are presented which account in various ways for stability of the equilibrium with respect to these perturbations.Work conducted while visiting the University of Bremen, supported by the Deutscheforschungsgemeinschaft.