A connection between the Henon-Heiles system and the Garnier system

A remarkable map between the generalized Henon-Heiles system and the Garnier system is obtained by means of a detailed comparison between two finite-dimensional reduction methods for soliton equations: thestationary flows and therestricted flows. The role of the Gelfand-Dickey polynomials and of the KdV Poisson pencil in this construction is emphasized.Dipartimento di Scienze Matematiche, Università degli Studi di Trieste, Piaz.le Europa 1, I34127 Trieste, Italy. E-mail: tondo@univ.trieste.it. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 99, No. 3, pp. 552–559, June, 1994.     

Imidazolium-based zwitterionic surfactant: a new amphiphilic Pd nanoparticle stabilizing agent

Palladium nanoparticles (NPs) with an average size of 3.4 nm were prepared in water using imidazolium-based surfactant 3-(1-dodecyl-3-imidazolio)propanesulfonate (ImS3-12) as a stabilizer. The Pd NPs are highly dispersible in water and chloroform and were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and dynamic light scattering. The results indicate that in water the NP surface is covered with a double layer of ImS3-12 molecules. The NPs were effective in the aqueous biphasic hydrogenation of cyclohexene, with easy recycling and no loss of catalytic activity after four successive runs.     

Reduction of bi-Hamiltonian systems and separation of variables: An example from the Boussinesq hierarchy

We discuss the Boussinesq system with the stationary time t₅ within a general framework of stationary flows of n-Gel'fand-Dickey hierarchies. A careful use of the bi-Hamiltonian structure can provide a set of separation coordinates for the corresponding Hamilton-Jacobi equations. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 122, No. 2, pp. 219–238, February, 2000.     

Silver electrodeposition from water–acetonitrile mixed solvents and mixed electrolytes in the presence of tetrabutylammonium perchlorate. Part I—electrochemical nucleation on glassy carbon electrode

Nucleation and growth of silver, electrodeposited from water–acetonitrile (CH₃CN from 0 to 100% by volume) mixed solvents on glassy carbon electrodes, was studied by means of double-sweep voltammetry, current–time transients (CTT) and scanning electron microscopy (SEM). The effects of the addition of the specifically interacting tetrabuthylammonium cation were also investigated. From voltammetries, the formal potential, the nucleation potential and the cathodic current efficiency have been evaluated as a function of the mixed solvent composition. The key role on nucleation kinetics of transferring Ag⁺ from the bulk phase to the CH₃CN-enriched electrode/solution interphase has been highlighted. CTT transients were described by a model combining instantaneous and progressive nucleation mechanisms. SEM images highlighted the effects of the presence of the organic solvent, which yields to a more regular growth, and of the quaternary ammonium salt, which exhibits grain-refining properties.     

Self-aggregated perfluoroalkylated hexa-peri-hexabenzocoronene fibers observed by cryo-SEM and fluorescence spectroscopy

The self-assembled architectures in solution of a new HBC derivative bearing perfluoroalkylated side chains were investigated by optical excitation and emission spectroscopy and correlated to cryo-SEM, a new technique in organic chemistry.     

The chameleon-like nature of zwitterionic micelles: effect of cation binding

Addition of salts, especially perchlorates, to zwitterionic micelles of SB3-14, C(14)H(29)NMe(2)(+)(CH(2))(3)SO(3)(-), induces anionic character and uptake of H(3)O(+) by SB3-14 micelles. Thus, the addition of alkali metal perchlorates accelerates the acid hydrolysis of 2-(p-heptoxyphenyl)-1,3-dioxolane, HPD, in the presence of SB3-14 micelles, which depends on the local proton concentration at the micelle surface. The addition of metal chlorides to solutions of such perchlorate-modified SB3-14 micelles decreases both the negative zeta potential of the micelles and the observed rate constant for acid hydrolysis of HPD. The effect of the monovalent cations Li(+), Na(+), and K(+) is smaller than that of the divalent cations Be(2+), Mg(2+), and Ca(2+), and much smaller than that of the trivalent cations Al(3+), La(3+), and Er(3+). The major factor responsible for this cation valence dependence of these effects is shown to be electrostatic in nature, reflecting the strong dependence of the micellar surface potential on the cation valence. The fact that the salt effects are not identical after correction for the electrostatic effects indicates that additional secondary nonelectrostatic effects may contribute as well.     

Pentaguanidinium monohydrogendiphosphopentamolybdate(VI) 2.5‐hydrate, (CH6N3)5[HP2Mo5O23]·2.5H2O: hydrogen bonding and π‐stacking in guanidinium cations

The asymmetric unit of the title compound consists of two crystallographically independent, but structurally identical, [HP₂Mo₅O₂₃]⁵⁻ anions, ten guanidinium cations and five water molecules. Each singly protonated diphosphopentamolybdate(VI) anion retains the typical geometry of a ring of five edge‐sharing MoO₆ octahedra [Mo...Mo = 3.3265 (8)–3.4029 (10) Å], except for one corner‐sharing link [Mo...Mo = 3.6642 (7) and 3.6826 (8) Å]. Two capping PO₄ tetrahedra share corners with the five octahedra. Despite being surrounded by an extensive network of hydrogen bonds, predominantly from the guanidinium cations, short P—O—H...O=P contacts [O...O = 2.519 (7) and 2.457 (7) Å] associate the anions into infinite columns generated by the c‐glide. In addition to their heavy involvement in hydrogen bonding, with all N—H donors being utilized, the guanidinium cations assemble into extensive π‐stacked columns with an average interplanar spacing of 3.53 Å.     

The chameleon-like nature of zwitterionic micelles. Control of anion and cation binding in sulfobetaine micelles. Effects on acid equilibria and rates

The rate of specific hydrogen ion catalyzed hydrolysis of 2-(p-heptoxyphenyl)-1,3-dioxolane and equilibrium protonation of 1-hydroxy-2-naphthoate ion in zwitterionic micelles of SB3-14, C14H29NMe2+(CH2)3SO3-, are increased markedly by NaClO4 which induces anionic character and uptake of H3O+ in the micelles. Other salts, for example, NaNO3, NaBr, and NaCl, have similar but much smaller effects on this uptake of H3O+.     

Haantjes Algebras of the Lagrange Top

We study a symplectic-Haantjes manifold and a Poisson–Haantjes manifold for the Lagrange top and compute a set of Darboux–Haantjes coordinates. Such coordinates are separation variables for the associated Hamilton–Jacobi equation.     

Silver electrodeposition from water–acetonitrile mixed solvents. Part III—an in situ investigation by optical second harmonic generation spectroscopy

In this work, we report an investigation based on silver electrodeposition from water–acetonitrile mixed solvents onto a polycrystalline Au electrode, based on in situ optical second harmonic generation (SHG) spectroscopy. This paper is the last one of a series attacking the same topic by cyclic voltammetry and potentiostatic current transients (Mele et al., J Solid State Electrochem in press, 1) and in situ surface-enhanced Raman scattering (Mele et al., J Solid State Electrochem in press, 2). SHG intensity transients following the application of potentiostatic cathodic steps have been measured in order to obtain detailed information on the formation of Ag clusters and nuclei during the electrodeposition process. Our SHG data have been rationalised in terms of a simple optical model accounting for SHG enhancement brought about by Ag cluster formation.