For every positive integer n let p(n) be the largest prime number p ≤ n. Given a positive integer n = n1, we study the positive integer r = R(n) such that if we define recursively ni+1 = ni − p(ni) for i ≥ 1, then nr is a prime or 1. We obtain upper bounds for R(n) as well as an estimate for the set of n whose R(n) takes on a fixed value k.

In the crystal structure of title compound, [NiCl(2)(C(14)H(32)P(2))], the Ni(II) atom lies on a twofold rotation axis and shows a slightly distorted square-planar coordination geometry, with a dihedral angle of 10.01 (8)° between the cis-Cl-Ni-Cl and cis-P-Ni-P planes. There is no significant inter-molecular inter-action except very weak C-H⋯Cl inter-actions. The crystal studied was a racemic ...

Nanoscale bimetallic Ni/Fe particles were synthesized from the reaction of sodium borohydride (NaBH4) with reduction of Ni2+ and Fe2+ in aqueous solution. The obtained Ni/Fe particles were characterized by TEM (transmission electron microscope), XRD (X-ray diffractometer), and N2-BET. The dechlorination activity of the Ni/Fe was investigated using p-chlorophenol (p-CP) as a probe agent. Results...

BACKGROUND Occupational exposure to nickel (Ni) is associated with an increased risk for lung and nasal cancers. Ni compounds exhibit weak mutagenic activity, cause gene amplification, and disrupt cellular epigenetic homeostasis. However, the Ni-induced changes in global histone modification levels have only been tested in vitro. OBJECTIVE This study was conducted in a Chinese population to d...

The use of the power and energy functional in the analysis of the electric circuits makes it possible to appreciate the energetic equilibrium state attained in the circuit at a certain moment. This paper is concerned with a demonstration of the principle of minimum dissipated active power for the steady state circuits under nonsinusoidal conditions. It is shown that the equilibrium state is one...

Treatment of Ni(NCS)2(PMe2Ph)2 with organic isocyanides CN-R gave five-coordinate isocyanide Ni(II) complexes, Ni(CN-R)(NCS)2(PMe2Ph)2 (R = C6H3-2,6-Me2 (1), t-Bu (2)). Interestingly, the corresponding reaction of Ni(NCS)2(P(n-Pr)3)2 with 2 equiv. of CN-t-Bu gave an unusual compound, which exists as an ion pair of the trigonal bipyramidal cation [Ni(P(n-Pr)3)2(CN-t-Bu)3]2+ (3) and the dinuclear...

Bond paths and the bond critical point properties (the electron density (rho) and the Hessian of rho at the bond critical points (bcp's)) have been calculated for the bonded interactions comprising the nickel sulfide minerals millerite, NiS, vaesite, NiS(2), and heazlewoodite, Ni(3)S(2), and Ni metal. The experimental Ni-S bond lengths decrease linearly as the magnitudes of the properties each ...

The first peak of the RDF has been calculated for the dense random packed (DRP) and Ni3P structures with a gaussian broadening of the atomic positions. It is found that the position of the broadened first peak of the RDF of DRP is 2 % greater than the hard sphere diameter. The contributions of Ni-Ni and NI-P pairs to the first peak of the RDF of amorphous Ni-P are discussed by comparing this pe...