A new model for a mode-locked semiconductor laser

We consider a new model for passive mode locking in a semiconductor laser comprising a set of delay differential equations. Bifurcations leading to the appearance and break-up of the mode-locking regime are studied numerically.     

Mechanism of the radiolytic transformations of cellulose 1. Formation and transformation of radicals

The formation (77K) and transformation (300K) of radicals in celluloses with various degrees of crystallinity under -radiation have been studied by the ESR method. The radical products of the low-temperature -radiolysis of cellulose formed in the polymer chain are macroradicals the unshared electrons of which are localized on C₍₁₎ C₍₄₎, O_(O), and C₍₅₎. With a rise in the temperature to 300K they undergo substantial changes, which shows the dominating role of secondary reactions of macroradicals in the radiation-chemical transformation of cellulose.A. S. Sadykov Institute of Organic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 62 70 71. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 587–595, July–August, 1996. Original article submitted February 26, 1996.     

Use of Ion-Exchange Membranes in Chemical Power Cells

A chemical power cell is suggested, in which the positive and negative electrodes are placed each in its own electrolyte. This makes it possible to obtain the highest absolute value of the electrode potential of each electrode. The electromotive force and the maximum theoretical specific energy are calculated for an acid-alkaline-salt battery of the zinc-dioxide-lead system.     

Breakdown of symmetry in reversible systems

We review results on local bifurcations of codimension 1 in reversible systems (flows and diffeomorphisms) which lead to the birth of attractor-repeller pairs from symmetric equilibria (for flows) or periodic points (for diffeomorphisms).     

Zinc-Bromine Alkali-Salt Membrane Chemical Power Cell

Zinc-bromine alkali-salt membrane-type chemical power cell was assembled and studied. The open-circuit voltage (OCV) of the zinc-bromine alkali-salt membrane chemical power cell (CPC) was experimentally obtained (2.30 V). This value is close to the theoretically calculated value of the electromotive force (EMF) of the cell (2.27 V) and exceeds the EMF and OCV of many known power cells using a single homogeneous-composition aqueous electrolyte and having no ion-exchange membrane. The maximum theoretical specific energy of the zinc-bromine alkali-salt membrane CPC is 317.3 W h kg^–1, which is lower that the corresponding values for the zinc-silver and zinc-nickel power cells and exceeds that of nickel-iron, nickel-cadmium, and lead sulfuric acid CPCs. It is shown that the cell under study can be used as an electric battery.     

Estimation of ion scattering by atomic chains on single crystal surfaces

Estimation of ion movement close to atomic chains taking into account the elastic and inelastic energy losses and vacancy type imperfections was performed on the basis of a model of binary interactions of ions with the atoms of a crystal.

An analysis of results shows that at scattering by atomic chains a phenomenon which makes a substantial contribution to scattering by the single crystal surface the inelastic energy losses exceed the single scattering ones by a factor of 5–6.