Norsk Hydro

About: Norsk Hydro is a company organization based out in Grevenbroich, Germany. It is known for research contribution in the topics: Magnesium & Aluminium. The organization has 2704 authors who have published 2837 publications receiving 78789 citations. The organization is also known as: Hydro & Norsk Hydro-Elektrisk Kvælstofaktieselskab.

Preparation of isolated rat liver cells.

Abstract: Publisher Summary This chapter discusses preparation of isolated rat liver cells The early mechanical and chemical methods for liver-cell preparation were relatively successful in converting liver tissue to a suspension of isolated cells The successful preparation of intact liver cells by perfusion with collagenase is technically quite difficult The major method for preparation of nonparenchymal liver cells is based on the selective sensitivity of parenchymal cells toward proteases By incubation of rat liver minces with pronase, most of the liver parenchyma is digested, while nonparenchymal cells remain intact and can be recovered from the incubate Similar results have been reported with trypsin digestion of collagenase-dispersed liver minces, but pronase appears to be more effective The most common procedure is to perfuse the liver briefly with pronase before it is minced and incubated with the enzyme Such direct pronase methods have been used by several investigators with yields of nonparenchymal liver cells reported to be in the range 2–15 × 10 6 cells/gm liver

QUASI: A general purpose implementation of the QM/MM approach and its application to problems in catalysis

Abstract: We describe the work of the European project QUASI (Quantum Simulation in Industry, project EP25047) which has sought to develop a flexible QM/MM scheme and to apply it to a range of industrial problems. A number of QM/MM approaches were implemented within the computational chemistry scripting system, ChemShell, which provides the framework for deploying a variety of independent program packages. This software was applied in several large-scale QM/MM studies which addressed the catalytic decomposition of N 2 O by Cu-containing zeolites, the methanol synthesis reaction catalysed by Cu clusters supported on ZnO surfaces, and the modelling of enzyme structure and reactivity.

Crude-oil biodegradation via methanogenesis in subsurface petroleum reservoirs

Abstract: Biodegradation of crude oil in subsurface petroleum reservoirs has adversely affected the majority of the world's oil, making recovery and refining of that oil more costly. The prevalent occurrence of biodegradation in shallow subsurface petroleum reservoirs has been attributed to aerobic bacterial hydrocarbon degradation stimulated by surface recharge of oxygen-bearing meteoric waters. This hypothesis is empirically supported by the likelihood of encountering biodegraded oils at higher levels of degradation in reservoirs near the surface. More recent findings, however, suggest that anaerobic degradation processes dominate subsurface sedimentary environments, despite slow reaction kinetics and uncertainty as to the actual degradation pathways occurring in oil reservoirs. Here we use laboratory experiments in microcosms monitoring the hydrocarbon composition of degraded oils and generated gases, together with the carbon isotopic compositions of gas and oil samples taken at wellheads and a Rayleigh isotope fractionation box model, to elucidate the probable mechanisms of hydrocarbon degradation in reservoirs. We find that crude-oil hydrocarbon degradation under methanogenic conditions in the laboratory mimics the characteristic sequential removal of compound classes seen in reservoir-degraded petroleum. The initial preferential removal of n-alkanes generates close to stoichiometric amounts of methane, principally by hydrogenotrophic methanogenesis. Our data imply a common methanogenic biodegradation mechanism in subsurface degraded oil reservoirs, resulting in consistent patterns of hydrocarbon alteration, and the common association of dry gas with severely degraded oils observed worldwide. Energy recovery from oilfields in the form of methane, based on accelerating natural methanogenic biodegradation, may offer a route to economic production of difficult-to-recover energy from oilfields.

An Introduction to Multipoint Flux Approximations for Quadrilateral Grids

Abstract: Control-volume discretizations using multipoint flux approximations (MPFA) were developed in the last decade. This paper gives an introduction to these methods for quadrilateral grids in two and three dimensions. The introduction is kept on a basic level, and a brief summary to more advanced results is given. Only the O-method with surface midpoints as continuity points is discussed. Flux expressions are derived both in physical and in curvilinear space. Equations for calculation of the transmissibility coefficients are given, and an explicit solution is shown for constant coefficients. K-orthogonality, stability and monotonicity are discussed, and an iterative solution technique is presented. Two numerical examples close the paper.