Constraints on Contact Angles for Multiple Phases in Thermodynamic Equilibrium

For three or more fluid phases in thermodynamic equilibrium and in contact with a solid surface, the Young equation can be used to find relations between the contact angles for different pairs of fluids. For an n-fluid-phase system, n(n-1)/2 contact angles can be defined, but there are (n-1)(n-2)/2 constraints between them, leaving only n-1 independent values of the contact angle. These constraints are very powerful in limiting and determining possible types of wetting behavior. The consequences are discussed for three- and four-phase flow. They have important applications for the understanding of gas injection processes in petroleum reservoirs. Copyright 2001 Academic Press.     

General synthesis of mono-, di-, and tri-acetylated indoles from indolin-2-ones

Having developed the one-pot triacetylation of indolin-3-ones, we have now devised a simple two-step reaction sequences to produce di- and mono-acetylated indoles from indolin-2-ones. The indolin-2-ones were first subjected to acetylation in the presence of acetic anhydride and a catalytic amount of N,N-dimethylaminopyridine to give 2-acetoxy-1,3-diacetylindoles. Subsequently, an enzyme-assisted deacetylation resulted in the chemoselective deprotection of the acetoxy group to produce 1,3-diacetyl-2-hydroxyindoles. However, a chemical deacetylation of 2-acetoxy-1,3-diacetylinoles under mild basic or acidic conditions resulted in the formation of 3-acetyl-2-hydroxyindoles.     

Determination of Water-Oil Interfacial Area during 3-Phase Gravity Drainage in Porous Media

Water-oil interfacial area in porous media was determined in laboratory experiments using sand columns consisting of either 2 (water and oil) or 3 (water, oil, and air) fluid phases. Surfactant sorption at the water-oil interface was directly measured for a wide range of water, oil, and air saturations undergoing gravity drainage. Differing values of the water-oil interfacial tension were also examined. The Gibbs adsorption equation was then used to obtain values for the water-oil interfacial area. Both 2- and 3-phase water-oil experiments showed a linear increase in interfacial area with decreasing water saturation. Results also showed that interfacial areas were not affected by changes in interfacial tension. The interfacial areas in the 3-phase experiments were less than half the calculated values of the corresponding 2-phase experiments, which contradicts predictions from a conventional pore level analysis of 3-phase flow. Copyright 2000 Academic Press.     

Carbon-13 NMR spectra of some tetra- and pentacyclic triterpene methyl ethers

The carbon-13 NMR spectra have been recorded for representatives of three previously unexamined classes of pentacyclic triterpenes—lupanes, fernanes and arboranes. In addition to the spectra of lupeol methyl ether, cylindrin and arundoin, the spectra of a number of other triterpene methyl ethers are also recorded. The effect of methyl ether formation on the shilding values for carbons in the 3β-hydroxy-4,4-dimethyl- ring A system is defined.     

Signature of non-Fickian solute transport in complex heterogeneous porous media

We simulate transport of a solute through three-dimensional images of different rock samples, with resolutions of a few microns, representing geological media of increasing pore-scale complexity: a sandpack, a Berea sandstone, and a Portland limestone. We predict the propagators (concentration as a function of distance) measured on similar cores in nuclear magnetic resonance experiments and the dispersion coefficient as a function of Péclet number and time. The behavior is explained using continuous time random walks with a truncated power-law distribution of travel times: transport is qualitatively different for the complex limestone compared to the sandstone or sandpack, with long tailing, an almost immobile peak concentration, and a very slow approach to asymptotic dispersion.     

Synthesis and Intracellular Redox Cycling of Natural Quinones and Their Analogues and Identification of Indoleamine‐2,3‐dioxygenase (IDO) as Potential Target for Anticancer Activity

Natural quinones, often linked with cellular oxidation processes, exhibit pronounced biological activity. In particular, the structurally unique isothiazolonaphthoquinone aulosirazole, isolated from blue‐green alga, possesses selective antitumor cytotoxicity, although its mechanism of action is unknown. The first synthesis of aulosirazole uses a route centered upon a late‐stage regioselective Diels–Alder reaction. The structurally related natural product pronqodine A, an inhibitor of prostaglandin release, and analogues thereof, were also prepared for comparison. Biological evaluation of the compounds identified one potential target as the immunoregulatory enzyme indoleamine‐2,3‐dioxygenase (IDO). The isothiazoloquinones are also efficient substrates for the human quinone reductase NQO1, and undergo intracellular NQO1‐dependent redox cycling resulting in the generation of reactive oxygen species, and at lower doses have the potential to alter the ratio of intracellular oxidized to reduced pyridine nucleotides.     

How to predict viscous fingering in three component flow

In a WAG process (Water Alternate Gas), water and a miscible solvent (gas) are injected into a reservoir containing water and oil. The solvent will finger through the oil, leading to early breakthrough and poor recovery. Compared with a miscible flood, when only solvent is injected, fingering is supressed by the simultaneous injection of water, since this reduces the apparent mobility contrast between the injected and displaced fluids. The fingering in a miscible flood, with only hydrocarbon flowing, can be modelled successfully using a Todd and Longstaff fractional flow. In this paper, we demonstrate how to modify the effective Todd and Longstaff mobility ratio self-consistently to account for fingering in three component systems. The resultant empirical equations of flow are solved exactly in one dimension and are in excellent agreement with the averaged saturation and concentration profiles computed using two dimensional high resolution simulation, for a variety of injected water saturations, in both secondary and tertiary displacements.