A next generation, pilot-scale continuous sterilization system for fermentation media

A new continuous sterilization system was designed, constructed, started up, and qualified for media sterilization for secondary metabolite cultivations, bioconversions, and enzyme production. An existing Honeywell Total Distributed Control 3000-based control system was extended using redundant High performance Process Manager controllers for 98 I/O (input/output) points. This new equipment was retrofitted into an industrial research fermentation pilot plant, designed and constructed in the early 1980s. Design strategies of this new continuous sterilizer system and the expanded control system are described and compared with the literature (including dairy and bio-waste inactivation applications) and the weaknesses of the prior installation for expected effectiveness. In addition, the reasoning behind selection of some of these improved features has been incorporated. Examples of enhancements adopted include sanitary heat exchanger (HEX) design, incorporation of a “flash” cooling HEX, on-line calculation of F(o) and R(o), and use of field I/O modules located near the vessel to permit low-cost addition of new instrumentation. Sterilizer performance also was characterized over the expected range of operating conditions. Differences between design and observed temperature, pressure, and other profiles were quantified and investigated

Formation of nanostructure by self-assembly of an elastin peptide

Elastin and elastin-related peptides have great potential in the biomaterial field, because of their peculiar mechanical properties and spontaneous self-assembling behavior. Depending on their sequences and under appropriate experimental conditions, they are able to self-assemble in different fiber morphologies, including amyloid-like fibers. Temperature-triggered self-assembly of a small elastin peptide shows a novel complex aggregation mechanism as revealed by different microscopy techniques. The conformations of the peptide have been investigated in solution and in the aggregated state by different spectroscopic techniques (CD, NMR, FT-IR) and revealed that the conformations adopted by the peptides in water in the prefibrillar state correspond to those populated by other elastin peptides, mainly polyproline II helix (PPII) and random coil. Conversely, the aggregated state shows evidence for antiparallel cross-β structures. Our molecular studies highlight the important role of PPII conformation on the prefibrillar state, putting forward the hypothesis that aggregation takes place through addition of the monomer in the PPII conformation with preformed β-sheet aggregates and/or through direct interaction of PPII helices

DYNAMICS OF LASER ABLATED MGB2 PLASMA EXPANDING IN ARGON PROBED BY OPTICAL EMISSION SPECTROSCOPY

We have used time and space-resolved optical emission spectroscopy to study the expansion dynamics of the plasma generated by pulsed laser ablation of solid targets of the recently discovered superconducting MgB2 into a background Ar gas at different pressures. Our analysis clearly indicates that, above a fixed pressure, plasma propagation into Ar leads to both the formation of a shock wave, which causes a considerable increase of the fraction of excited Mg atoms, and the simultaneous reduction of the kinetic flux energy of the ablated atoms. These results have then been analyzed in the framework of a simplified gas dynamic approach for the description of free-plume self-similar expansion and of a point-blast-wave model to account for the interaction of the plume with the Ar ambient gas, thus obtaining full support and a sound physical interpretation of our experimental observations. Finally, we have related our conclusions to the general problem of the optimization of the thin-film deposition of laser-ablated materials, with particular emphasis given to the specific case of MgB2, which is of great, present interest