Glass-fiber woven catalysts as alternative catalytic materials for various industries. A review

The chemistry and technology of new versatile multipurpose catalytic systems developed and studied by the authors for the purposes of heterogeneous catalysis are reviewed. A theoretical background for a successful search for these new catalytic systems is based on an unconventional approach with emphasis on an essential role of branched-chain reaction mechanisms of heterogeneous catalysis previously developed by the authoring team. The catalytic systems under study are based on silica (aluminoborosilicate) glass-fiber amorphous matrices doped with various metals and manufactured as articles with various types of woven structure. The specific features of these glass-fiber woven catalytic systems, such as their structure, phase state of the matrix, manufacture and activation methods, design of catalytic reactors in which they operate, as well as production technologies and operation methods, make a compelling case to regard them as a new separate class of catalysts. As compared to conventional catalytic materials, these new catalysts are highly efficient in neutralizing industrial gas emissions, in contact stages of the production of nitric acid and sulfuric acid, in various reactions of catalytic hydrocarbon processing, in water purification from nitrate and nitrite contaminants, in catalytic heat generation, etc

Breathing Current Domains in Globally Coupled Electrochemical Systems: A Comparison with a Semiconductor Model

Spatio-temporal bifurcations and complex dynamics in globally coupled intrinsically bistable electrochemical systems with an S-shaped current-voltage characteristic under galvanostatic control are studied theoretically on a one-dimensional domain. The results are compared with the dynamics and the bifurcation scenarios occurring in a closely related model which describes pattern formation in semiconductors. Under galvanostatic control both systems are unstable with respect to the formation of stationary large amplitude current domains. The current domains as well as the homogeneous steady state exhibit oscillatory instabilities for slow dynamics of the potential drop across the double layer, or across the semiconductor device, respectively. The interplay of the different instabilities leads to complex spatio-temporal behavior. We find breathing current domains and chaotic spatio-temporal dynamics in the electrochemical system. Comparing these findings with the results obtained earlier for the semiconductor system, we outline bifurcation scenarios leading to complex dynamics in globally coupled bistable systems with subcritical spatial bifurcations.Comment: 13 pages, 11 figures, 70 references, RevTex4 accepted by PRE http://pre.aps.or

Current-induced magnetic superstructures in exchange-spring devices

We investigate the potential to use a magneto-thermo-electric instability that may be induced in a mesoscopic magnetic multi-layer (F/f/F) to create and control magnetic superstructures. In the studied multilayer two strongly ferromagnetic layers (F) are coupled through a weakly ferromagnetic spacer (f) by an "exchange spring" with a temperature dependent "spring constant" that can be varied by Joule heating caused by an electrical dc current. We show that in the current-in-plane (CIP) configuration a distribution of the magnetization, which is homogeneous in the direction of the current flow, is unstable in the presence of an external magnetic field if the length L of the sample in this direction exceeds some critical value Lc ~ 10 \mu m. This spatial instability results in the spontaneous formation of a moving domain of magnetization directions, the length of which can be controlled by the bias voltage in the limit L >> Lc. Furthermore, we show that in such a situation the current-voltage characteristics has a plateau with hysteresis loops at its ends and demonstrate that if biased in the plateau region the studied device functions as an exponentially precise current stabilizer.Comment: 8 pages, 6 figure

Propagation and ignition of fast gasless detonation waves of phase or chemical transformation in condensed matter

PACS. 82.20.Mj Nonequilibrium kinetics - 05.70.Ln Nonequilibrium and irreversible thermodynamics,