Synchronization of Distributed Electron–Wave Self-Oscillatory Systems with a Backward Wave

We present the results of studying the phenomenon of synchronization in distributed electron–wave self-oscillatory systems with a counterpropagating wave. General laws governing the appearance of the classical synchronization in distributed systems are revealed. We propose methods for increasing the synchronization bandwidth by using the distributed input of a signal to the interaction space by means of coupled waveguide structures. Transient processes in nonautonomous self-oscillation regimes are studied. In particular, the effect of ultrafast synchronization is found. The possibility of chaotic synchronization in a gyro-oscillator with a counterpropagating wave under the action of a deterministic chaotic signal is shown. Mutual oscillation regimes in a system of two distributed oscillators with coupled waveguide systems are studied.     

Synthetic analogs of active centers of iron-sulfur proteins: Reactions with phosphates

The interaction of synthetic analogs of active centers of iron-sulfur proteins with phosphates of different structures was studied. It was shown that the process involves ligand exchange and obeys the first-order reaction kinetic equation. The most rapid exchange occurred with the most acidic compound diphenyl phosphate.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2301–2305, October, 1992.     

Enhanced microdialysis recovery of some tricyclic antidepressants and structurally related drugs by cyclodextrin-mediated transport

The enhanced microdialysis relative recovery (RR) of some hydrophobic tricyclic drugs (imipramine, desipramine, amitriptyline, carbamazepine and promethazine) is discussed. Enhanced RR was achieved by including a binding agent [beta-cyclodextrin (beta-CD) or 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD)] in the microdialysis perfusion fluid to form inclusion complexes with the drugs, which increases the analyte flux through the membrane material. The maximum effect of the RR increase for all the drugs studied was observed using a commercially available polycarbonate-polyether (PC) membrane. With a 4 mm PC membrane and 4.41 mmol l-1 (0.5% w/v) beta-CD included in the microdialysis perfusion fluid (0.9% saline, pH 7.4) at a flow rate of 0.5 microliter min-1, RR enhancements over controls were as follows: carbamazepine 136, imipramine 268, desipramine 298, amitriptyline 634, and promethazine 987%. Increasing beta-CD [up to 17.63 mmol l-1 (2% w/v)] or HP-beta-CD [up to 32.5 mmol l-1 (5% w/v)] concentration in the microdialysis perfusion fluid enhanced carbamazepine RR three (beta-CD) to four (HP-beta-CD) times compared to controls through PC microdialysis membranes. The PC membrane gave enhanced RR values that were twice those for cuprophan or AN-69 membranes. Enhanced RR with cyclodextrins was successfully applied to sampling from a protein solution containing desipramine in a 4% w/v bovine serum albumin solution. These results suggest that addition of cyclodextrins to microdialysis perfusion fluids may be used to increase microdialysis RR during blood sampling.     

Structure of the Mo-Containing Dispersed Catalyst During Heavy Oil Upgrading in the Presence of Steam And Hydrogen

XRD, TEM, EXAFS/XANES methods are first used to study the structure and morphology of Mocontaining phases of carbon residues of heavy oil refining during catalytic steam cracking, catalytic cracking without water, and hydrocracking. According to the results obtained from physical and chemical studies of Mo-based catalytic phases, the reaction medium affects structural features of Mo-containing phases, e.g. the amount of oxide and sulphide forms, the particle size, and particle morphology.     

Choosing the state of a spatially distributed system in calculating a spectrum of Lyapunov exponents

The problem of choosing the set of parameters that determine the state of a spatially distributed system when calculating a spectrum of Lyapunov exponents is considered. The possibility of reducing the number of necessary quantities due to the features of the employed mathematical model is discussed. The proposed method is successfully applied to a hydrodynamic model of a Piers diode.     

Phenomenon of generalized synchronization in klystron chaos generators with delayed feedback: Experiment and numerical simulation

The system of unidirectionally coupled klystron chaos generators with delayed feedback has been experimentally and theoretically investigated. A new technique for diagnostics of generalized chaotic synchronization is proposed, which is based on the spectral analysis of a signal from a response klystron generator. Comparison of the obtained experimental and theoretical results is performed.     

Synthesis and study of redox-active acyclic triazenes: toward electrochromic applications

Coupling of various 4-substituted phenyl azides with two distinct quinone-containing N-heterocyclic carbenes (NHCs) afforded the respective mono- and ditopic 1,3-disubstituted acyclic triazenes in moderate to excellent yields (38-92%). Depending on their pendant substituents (derived from the azides), the acyclic triazenes exhibited intense absorptions in the visible spectrum (359-428 nm), which were bathochromically shifted by up to Δλ=68 nm upon reduction of the quinone moiety on the component derived from the NHC. Cyclic voltammetry confirmed that the aforementioned redox processes were reversible, and a related set of UV-vis spectroelectrochemical experiments revealed that bulk electrolysis may also be used to switch reversibly the colors exhibited by these triazenes.     

A new multidimensional chromatographic technique: Liquid chromatography with a multiphase eluent

Summary A novel form of liquid chromatography is described which involves the use of multiphase eluents, such as emulsions, for the separation of biopolymers and certain microorganisms.Presented at the 14th International Symposium on Chromatography London, September, 1982