in this study, nickel-phosphorus coating was prepared by electrodeposition technique on the 304 stainless steel substrate. the effects of current density, phosphorous acid concentration, time and ph on the phosphorous content was investigated using taguchi method. a uniform amorphous-nanocrystalline structure (ni-12%p) was obtained. sem, eds, tem and xrd were used in order to study the surface ...

Semiclassical periodic-orbit theory and closed-orbit theory represent a quantum spectrum as a superposition of contributions from individual classical orbits. Close to a bifurcation, these contributions diverge and have to be replaced with a uniform approximation. Its construction requires a normal form that provides a local description of the bifurcation scenario. Usually, the normal form is c...

Spherically confined dust crystals have recently attracted large attention, see e.g. [1] and [2] for an overview. After the exploration of the ground state structure [3, 4, 5, 6] and of metastable states and their probability [7, 8, 9] a question of particular interest is the dynamical excitation spectrum. The normal modes are a key property describing the response of a finite system to externa...

Calix[4]arenes substituted at their wide rim by four aryl urea residues (1) form hydrogen-bonded dimers in apolar solvents. Replacement of one urea residue by an acetamido moiety leads to calix[4]arene derivatives (5) which form hydrogen-bonded tetramers under the same conditions. Both self-assembly processes occur independently. Therefore, molecules have been prepared in which a tetra-urea cal...

We explore the existence of uniformly continuous sections for quotient maps. Using this approach we are able to give a number of new examples in the theory of the uniform structure of Banach spaces. We show for example that there are two non-isomorphic separable L1-subspaces of 1 which are uniformly homeomorphic. We also prove the existence of two coarsely homeomorphic Banach spaces (i.e. with ...