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We discuss the problem of building domain oriented environments by a composition of heterogeneous application components and tools. We describe several individual tools that support such environments, namely a distributed monitoring and control tool (DAMS), a process-based distributed debugger (PDBG) and a heterogeneous interconnection model (PHIS). We discuss our experience with the development of a Problem Oriented Environment in the domain of genetic algorithms, obtained by a composition of heterogeneous tools and application components.

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Rapid freeze-quench (RFQ) Mossbauer and stopped-flow absorption spectroscopy were used to monitor the ferritin ferroxidase reaction using recombinant (apo) frog M ferritin; the initial transient ferric species could be trapped by the RFQ method using low iron loading (36 Fe2+/ferritin molecule). Biphasic kinetics of ferroxidation were observed and measured directly by the Mossbauer method; a majority (85%) of the ferrous ions was oxidized at a fast rate of similar to 80 s(-1) and the remainder at a much slower rate of similar to 1.7 s(-1). In parallel with the fast phase oxidation of the Fe2+ ions, a single transient iron species is formed which exhibits magnetic properties (diamagnetic ground state) and Mossbauer parameters (Delta E-Q = 1.08 +/- 0.03 mm/s and delta = 0.62 +/- 0.02 mm/s) indicative of an antiferromagnetically coupled peroxodiferric complex. The formation and decay rates of this transient diiron species measured by the RFQ Mossbauer method match those of a transient blue species (lambda(max) = 650 nm) determined by the stopped-flow absorbance measurement. Thus, the transient colored species is assigned to the same peroxodiferric intermediate. Similar transient colored species have been detected by other investigators in several other fast ferritins (H and M subunit types), such as the human H ferritin and the Escherichia coli ferritin, suggesting a similar mechanism for the ferritin ferroxidase step in all fast ferritins. Peroxodiferric complexes are also formed as early intermediates in the reaction of O-2 With the catalytic diiron centers in the hydroxylase component of soluble methane monooxygenase (MMOH) and in the D84E mutant of the R2 subunit of E. coli ribonucleotide reductase. The proposal that a single protein site, with a structure homologous to the diiron centers in MMOH and R2, is involved in the ferritin ferroxidation step is confirmed by the observed kinetics, spectroscopic properties, and purity of the initial peroxodiferric species formed in the frog M ferritin.

We discuss the problem of building domain oriented environments by a composition of heterogeneous application components and tools. We describe several individual tools that support such environments, namely a distributed monitoring and control tool (DAMS), a process-based distributed debugger (PDBG) and a heterogeneous interconnection model (PHIS). We discuss our experience with the development of a Problem Oriented Environment in the domain of genetic algorithms, obtained by a composition of heterogeneous tools and application components.

The aim of this work is to present a model able to explain the role of the lateral drift current on the experimental behaviour exhibited by p-i-n amorphous silicon solar cells (J-V characteristics, responsivity and the apparent device degradation behaviour), when the ratio between the covered and uncovered metal collected areas of the device is higher than one or recrystallization occurs in the edges of the p-i-n junction.

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