Products from the trimethylamine N-oxide activation reaction of Ru4(CO)12(μ 4-C6H8) with cyclohexa-1,3-diene

Summary Reaction of Ru₄(CO)₁₂( ₄-C₆H₈) (1) with three equivalents of Me₃NO and cyclohexa-1,3-diene in CH₂Cl₂ (195–295 K) gives one major product, the benzene butterfly cluster Ru₄(CO)₉( ₄-C₆H₈)( ⁶-C₆H₆) (2), in which the benzene is coordinated to a wing-tip Ru atom. Three other products are formed in lower yield, these comprised of an isomer of the aforementioned cluster in which the benzene is attached to a hinge Ru atom (3), the bis(cyclohexadiene) cluster Ru₄(CO)₈( ₄-C₆H₈)( ⁴-C₆H₈)₂ (4), and the trinuclear species Ru₃(CO)₈( ₃-C₆H₈)( ⁴-C₆H₈) (5). The characterization of the new compounds (4) and (5) is described, including the solid-state structure of (4) determined by a single crystal X-ray diffraction analysis.     

Oblique stagnation slip flow of a micropolar fluid

This paper considers the problem of steady two-dimensional boundary layer flow of a micropolar fluid near an oblique stagnation point on a fixed surface with Navier’s slip condition. It is shown that the governing nonlinear partial differential equations admit similarity solutions. The resulting nonlinear ordinary differential equations are solved numerically using the Keller box method for some values of the governing parameters. It is found that the flow characteristics depend strongly on the micropolar and slip parameters.     

The motion of a semi-infinite bubble between parallel plates

The motion of a two-dimensional bubble which is moving between two parallel plates under the influence of a constant pressure has been investigated using the Boundary Element Method. A free surface location algorithm has been developed so that the profile of the bubble may be predicted over a large range of values of the surface tension. The numerically predicted results are compared with existing experimental data and the results are encouraging.     

Transient free convection about a horizontal circular cylinder in a porous medium

The method of matched asymptotic expansions is employed for investigating the growth of the free convection boundary-layer on a horizontal circular cylinder which is embedded in a porous medium. It is assumed that the Rayleigh number is large, but finite, and the time of investigation is short. It is shown that the solution contains terms that are absent from the solution based on the boundary-layer approximation and that vortices form at both sides of the cylinder. The development of the plume region near the top of the cylinder, as well as the local and average Nusselt numbers, are evaluated and presented in graphical form.     

Conversion of bioprocess ethanol to industrial chemical products

Applied Biochemistry and Biotechnology - Ethanol is commercially produced by bioconversion and by hydration of ethylene. Bioconversion has the significant advantage that utilization of nonrenewable...     

Optical model analysis of proton-carbon elastic scattering in the range 20 to 50 MeV

The differential cross-sections for the elastic scattering of protons from¹²C with incident energies ranging in approximately 2 MeV steps between 20 and 50 MeV, are analyzed using a standard optical model.     

Nonequilibrium 2-hydroxyoctadecanoic acid monolayers: effect of electrolytes

2-Hydroxyacids display complex monolayer phase behavior due to the additional hydrogen bonding afforded by the presence of the second hydroxy group. The placement of this group at the position α to the carboxylic acid functionality also introduces the possibility of chelation, a utility important in crystallization including biomineralization. Biomineralization, like many biological processes, is inherently a nonequilibrium process. The nonequilibrium monolayer phase behavior of 2-hydroxyoctadecanoic acid was investigated on each of pure water, calcium chloride, sodium bicarbonate and calcium carbonate crystallizing subphases as a precursor study to a model calcium carbonate biomineralizing system, each at a pH of ～6. The role of the bicarbonate co-ion in manipulating the monolayer structure was determined by comparison with monolayer phase behavior on a sodium chloride subphase. Monolayer phase behavior was probed using surface pressure/area isotherms, surface potential, Brewster angle microscopy, and synchrotron-based grazing incidence X-ray diffraction and X-ray reflectivity. Complex phase behavior was observed for all but the sodium chloride subphase with hydrogen bonding, electrostatic and steric effects defining the symmetry of the monolayer. On a pure water subphase hydrogen bonding dominates with three phases coexisting at low pressures. Introduction of calcium ions into the aqueous subphase ensures strong cation binding to the surfactant head groups through chelation. The monolayer becomes very unstable in the presence of bicarbonate ions within the subphase due to short-range hydrogen bonding interactions between the monolayer and bicarbonate ions facilitated by the sodium cation enhancing surfactant solubility. The combined effects of electrostatics and hydrogen bonding are observed on the calcium carbonate crystallizing subphase.