Intrinsic bioremediation of gas condensate hydrocarbons

Condensate liquids have been found to contaminate soil and ground water at two gas production sites in the Denver Basin operated by Amoco Production Co. These sites have been closely monitored since July 1993 to determine whether intrinsic aerobic or anaerobic bioremediation of hydrocarbons occurs at a sufficient rate and to an adequate end point to support a no-intervention decision. Ground water monitoring, soil gas analysis, and analysis of soil cores suggest that bioremediation is occurring at these sites by multiple pathways, including aerobic oxidation, sulfate reduction, and methanogenesis. Results of over two years of monitoring of ground water and soil chemistry at these sites are presented to support this conclusion.

     

Lattice Boltzmann simulations of electrolysis reactions: Microfluidic voltammetry

A lattice Boltzmann model was used to simulate electrolysis reactions occurring within reactors where fluid is pumped through the device under microfluidic control. This article describes the application of two- and three-dimensional procedures for the simulation of the fluid velocities and mass transport characteristics within reactors of an arbitrary geometry. The lattice Boltzmann method is used to simulate the mass transport limited reduction of a species at a large planar electrode, embedded within one wall of a rectangular duct, under either steady-state or potential step conditions. The results of the simulations are compared to both those predicted analytically and via Finite Difference methods for this geometry and used to assess the accuracy of the approach. Good agreement is found between the lattice Boltzmann models and the well-established analytical theory, highlighting the potential of this approach for electrochemical applications within microfluidic environments. A major benefit of the lattice Boltzmann approach is the simple extension of the method to more complex cell and electrode geometries; the potential benefits of this are also noted.     

Copper(II) complex of the chelating agent EDTA bis(tyrosine)

The synthesis technique is given and the results of X-ray study of a copper(II) compound, Cu(O₁₂N₄C₂₈H₃₀)·7H₂O, are reported. The structure is molecular and the copper atom is coordinated by a distorted octahedron exhibiting a Jahn-Teller effect. The Cu-O(carbonyl) bond is 0.31 Å longer than the axial carboxylate to copper bonds.     

Reduction in the moisture absorption of cured MY720/DDS epoxy resins

Thin films of cured MY720/DDS epoxy resins were treated with blocking reagents for hydroxyl, amine, and epoxide functional groups. Infrared spectroscopy (IR) and differential scanning calorimetry (DSC) were used to monitor the progress of the reaction. Treated films were soaked in distilled water at 30°C for 720 h, and the corresponding moisture absorption determined gravimetrically. Samples treated with N-methyl-N-t-butyldimethylsilyl trifluroacetamide (MTBSTFA) containing 1% t-butyldimethylchlorosilane (TBDMCS) in dimethylsulfoxide (DMSO) at 30°C showed a maximum reduction in the IR peak at 3400 cm^?1 (OH and NH) of 39% and a 100% reduction in the epoxide peak at 904 cm, ^?1. The moisture absorption was 1.9%, a reduction of 58% compared to the untreated films (ca. 4.5%). The reactions show dependencies on time and temperature and are diffusion controlled. Samples treated with trimethylsilyl isocyanate (TMSI) in DMSO a 70°C showed 72% reduction in the 3400 cm^?1 IR peak; DSC thermograms do not show an exothermic energy, suggesting that all epoxide groups reacted. These reactions are primarily dependent on time and temperature. The moisture absorption of TMSI treated samples was 1.0% (75% reduction). Samples were also treated with m-trifluoromethyl phenyliscyanate (MTFPI). The reduction in the IR peak at 3400 cm^?1 was 9%, but the moisture absorption was 2.4%—a reduction of 47%.     

Effects of argon dilution on the translational and rotational temperatures of SiH in silane and disilane plasmas

The effects of argon dilution on the translational and rotational temperatures of SiH in both silane and disilane plasmas have been investigated using the imaging of radicals interacting with surfaces (IRIS) technique. The average rotational temperature of SiH determined from the SiH excitation spectra is approximately 500 K in both SiH(4)/Ar and Si(2)H(6)/Ar plasmas, with no obvious dependence on the fraction of argon dilution. Modeling of kinetic data yields average SiH translational temperatures of approximately 1000 K, with no dependence on the fraction of argon in the SiH(4)/Ar plasmas within the studied range. In the Si(2)H(6)/Ar plasmas, however, the translational temperature decreases from approximately 1000 to approximately 550 K as the Ar fraction in the plasma increases. Thus, at the highest Ar fractions, the translational and rotational temperatures are nearly identical, indicating that the SiH radicals are thermally equilibrated. The underlying chemistry and mechanisms of SiH energy equilibration in Ar-diluted plasmas are discussed.     

The Ising model in a random magnetic field

The existence of a spontaneous magnetization in the three-dimensional Ising model in a weak random magnetic field (RFIM) is investgated. Following Imry and Ma, we consider the energy change, E, from the fully aligned ferromagnetic state caused by flipping all the spins inside a connected surface, . It is proved rigorously that with high probability, E is positive forall enclosing the origin. Under the unproven assumption that the expectation value of the spin at one site is weakly correlated with the random fields at far away sites (which is true if surfaces within surfaces can be ignored) it follows that the three-dimensional RFIM has a spontaneous magnetization at low temperatures. The proof works for all dimensions greater than two, providing support for the conjecture that two is the lower critical dimension.Work supported in part by NSF grant No. DMR 8100417.     

Investigation of hydrothermal routes to mixed-metal cerium titanium oxides and metal oxidation state assignment using XANES

The reaction between TiF(3) or TiO(2) and Ce(3+) in sodium hydroxide solutions yields highly crystalline NaCeTi(2)O(6) at room temperature and under mild hydrothermal conditions (T < or = 240 degrees C). There is no evidence for the formation of ternary Ce-Ti-O materials by this method, and the use of bases other than NaOH always produces poorly crystalline materials. The material NaCeTi(2)O(6) has a distorted perovskite structure with sodium and cerium ions randomly occupying the A sites: Pnma, a = 5.4517(8) A, b = 7.7292(6) A, c =5.4573(3) A. XANES spectroscopy at the Ti K edge and Ce L(III) edge, with reference to crystalline model compounds, reveals that cerium is found solely as Ce(III) and titanium as Ti(IV) in NaCeTi(2)O(6). Isomorphous substitution of Ce(3+) by Nd(3+) or Ti(4+) by V(4+) is found to be very facile under hydrothermal conditions (at a temperature of 240 degrees C), by addition of appropriate amounts of metal salts to the hydrothermal reaction mixtures. The series NaCe(1-x)Nd(x)Ti2O6 (0 < or = x < or = 1) and NaCeTi(2-x)V(x)O6 (0 相似文献   

Solid-phase synthesis of 4-methylene pyrrolidines and allylic amines using palladium-activated allylic linkers

The solid-phase synthesis of 4-methylene pyrrolidines and allylic amines has been achieved using palladium-catalysed nucleophilic cleavage of allylic linkages. Six pyrrolidines were synthesised in five steps from a carboxyethyl resin 20, where the key transformations included a Lewis-acid promoted imino-Sakurai type reaction and reductive alkylation prior to the final palladium-catalysed cyclisation cleavage of the allylic carboxylate linkage. Allylic carboxylate resin 22 was also shown to undergo "traceless" cleavage using various hydride sources in the presence of catalytic palladium. A more robust allylic ether linkage was also investigated. Starting from a phenol resin 36, a number of 3-aryl-allylamines were prepared using a palladium-catalysed nucleophilic cleavage reaction.