Formation of acylruthenium promoted by coordination of AlMe(3) to (eta(4)-cyclopentadienone)Ru(CO)(3)

The reaction of AlMe(3) with (eta(4)-tetraphenylcyclopentadienone)Ru(CO)(3) leads to rapid and quantitative formation of an adduct arising from coordination of the enone oxygen to aluminium, which undergoes alkylation at the Ru(CO)(3) moiety to give (eta(5)-C(4)Ph(4)C(OAlMe(2)))Ru(CO)(2)(COMe) concomitant with a change of hapticity of the dienone ligand.     

Photoelectron angular distribution in valence shell ionization of heteroaromatic molecules studied by the continuum multiple scattering xalpha method

Photoelectron angular distributions are calculated for the valence shell ionization of heteroaromatic molecules of pyridine, pyrazine, pyrimidine, pyrrole, and furan by the continuum multiple scattering Xalpha method. The asymmetry parameters exhibit strong energy dependences in ionization from pi orbitals but are almost invariant in ionization from sigma orbitals, in good agreement with experimental results. The asymmetry parameters in ionization from nonbonding orbitals appear generally higher than those in ionization from bonding orbitals. These features are interpreted in terms of the Coulomb phase and photoelectron angular distribution in the molecular frame.     

Photoelectron kinetic energy dependence in near threshold ionization of NO from A state studied by time-resolved photoelectron imaging

Photoelectron angular distributions in the laboratory frame (LF-PADs) from the A((2)sigma(+)) state of NO molecule were measured by femtosecond time-resolved photoelectron imaging with (1 + 1(')) resonance enhanced multiphoton ionization via the A state. High-precision measurements of the anisotropy parameters of LF-PADs were performed for the photoelectron kinetic energy from 0.03 to 1.05 eV as a function of the pump-probe delay time. The revival feature of the rotational wave packet on the A state was clearly observed in the time dependence of the photoelectron anisotropy parameters. By approximating the phase shifts of the photoelectron partial waves by the quantum defects in the high-lying Rydberg states using the multichannel quantum defect theory, the energy-dependent photoionization transition dipole moments were determined, for the first time, from time-dependent LF-PADs measured by time-resolved photoelectron spectroscopy.     

Synthesis of the entire carbon framework of the kedarcidin chromophore aglycon

In advanced studies directed toward the total synthesis of the kedarcidin chromophore, we have successfully achieved the late-stage installation of the nine-membered diyne ring in the presence of the highly functionalised ansamacrocyclic bridge.     

Accurate Representation of Near-well Effects in Coarse-Scale Models of Primary Oil Production

Near-well effects can have a strong impact on many subsurface flow processes. In oil production, because dissolved gas is released from the oil phase when the pressure falls below the bubble point, the detailed pressure field in the immediate vicinity of a production well strongly impacts gas (and thus oil) production. This effect is complicated by the interplay of fine-scale heterogeneity and two-phase flow physics, and can be difficult to capture in coarse-grid simulations. In this article, we develop and apply a new upscaling (coarse-graining) procedure to capture such near-well subgrid effects in coarse-scale flow simulation models. The method entails the use of preprocessing computations over near-well domains [referred to as local well models (LWM)] for the determination of upscaled single-phase and two-phase near-well parameters. These parameters are computed by minimizing the mismatch between fine and coarse-scale flows over the LWM. Minimization is accomplished using a gradient-based optimization procedure, with gradients calculated through solution of adjoint equations. The boundary conditions applied on the LWM can impact the upscaled parameters, but these boundary conditions depend on the global flow and are not, therefore, known a priori. In order to circumvent this difficulty, an adaptive local–global procedure is applied. This entails performing a global coarse-scale simulation with initial estimates for well-block parameters. The resulting pressure and saturation fields are then used to define local boundary conditions for the near-well computations. The overall procedure is applied to several example problems and is shown to provide results in close agreement with reference fine-scale computations. Significant improvement in accuracy over existing near-well upscaling treatments is demonstrated, particularly for a heavy oil case with oil viscosity of ~10⁴ cp.     

Influence of Sn on the hydration of tricalcium aluminate, Ca3Al2O6

Tricalcium aluminate (Ca₃Al₂O₆, C₃A) containing 0?C5% of Sn was synthesized by solid-state method, and the products were characterized by XRD technique. Differential thermo-analytical technique (DTA) along with X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were applied to study the hydration behaviour of different C₃A samples with and without the presence of gypsum. Results indicate that C₃A can accommodate small amount of Sn in its structure and remaining amount forms SnO₂. Hydration studies of the synthesized C₃A shows that the additions of 0.5 and 1% Sn increase and 2% Sn decrease the reactivity of C₃A at the initial period (<3?h) of hydration. Increasing additions of Sn also increase the amounts of amorphous phases and hexagonal calcium aluminate hydrates in the cement pastes. The stabilities of these hydration products also increase with increasing content of Sn in C₃A at the experimental conditions. The presence of Sn significantly changes the hydration of C₃A and gypsum solid mixture at the initial period of hydration by enhancing the formation of more amounts of AFt and AFm phases. However, at the later stage of hydration (on or after 3?days), the hydration products in C₃A and gypsum pastes with and without the presence of Sn are almost similar.