The successive production of striations in a glow discharge in hydrogen

The manner of successive production of striations moving from the cathode to the anode in a glow discharge in hydrogen is experimentally investigated. For this purpose use is made of the method of an artifically produced transient process in the positive column. It is shown that the fundamental phenomenon in the production of these striations, similarly as with an inert gas, is the wave of stratification. The wave of stratification in hydrogen, however, differs from that in the plasma of an inert gas in the direction of motion of the striations. This direction in a hydrogen discharge is the same as the direction of the successive production of striations, i. e. from cathode to anode. The phenomenological theory of the successive production of moving striations elaborated earlier is also applicable for the wave of stratification in hydrogen.     

An Investigation of the Structure of Copolymers of lsobutylene and Diene Prepared by Initiation with VCI4 in the Dark and with Visible Light

¹H-NMR spectra of copolymers of isobutylene and 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene were investigated in connection with the elucidation of the formation of soluble and insoluble copolymers. For copolymers soluble in heptane, benzene, and CCI₄ it was found that the incorporation of diene into the polymer chain proceeds by 1,4-addition in the case of copolymerizations conducted both in the dark and with visible light using VC1₄ as initiator. The formation of a soluble and an insoluble copolymer is attributed to a different type of initiation, either with radical-cations of isobutylene, if soluble copolymers are formed, or with radical-cations of diene, if the arising copolymers are insoluble.     

Electrode potential-controlled DNA damage in the presence of copper ions and their complexes.

Supercoiled (sc) DNA immobilized at the surface of a hanging mercury drop electrode was cleaved by reactive oxygen species generated by an electrochemically modulated reaction of copper ions, hydrogen peroxide and/or oxygen. The cleavage was observed in a certain potential region where redox cycling of DNA-bound Cu(II)/Cu(I) took place. In the presence of 1,10-phenanthroline the maximum efficiency of DNA cleavage was shifted to more negative potentials and the effect was enhanced.     

The greedy coloring is a bad probabilistic algorithm

Given a graph G and an ordering p of its vertices, denote by A(G, p) the number of colors used by the greedy coloring algorithm when applied to G with vertices ordered by p. Let , , Δ be positive constants. It is proved that for each n there is a graph G_n such that the chromatic number of G_n is at most n, but the probability that A(G_n, p) < (1 − )n/log₂ n for a randomly chosen ordering p is O(n^−Δ).     

The oxidation of benzidine,o,o′-tolidine and o,o′-dianisidine with cobalt(III) perchlorate

The oxidation of benzidine, o,o′-tolidine and o,o′-dianisidine with cobalt(III) perchlorate was studied. The oxidation of benzidine and o,o′-tolidine involves two-electron exchange, is reversible and the appropriate quinonediimine is formed. No semiquinone is formed during the reaction in the studied medium.