Rejuvenation Of Used Turbine Blades By Hot Isostatic Processing

LecturePg. 55-60.The creep properties of gas turbine blades will deteriorate with prolonged service exposure. This deterioration is primarily due to internal microstructural changes and the formation of creep voids or cavitation. Development work has shown that HIP processing is the best available treatment for recovery of properties in used blades. The results obtained on a complete engine set of lnconel X-750 blades indicate that HIP processing is capable of restoring new or near new creep resistance to used blades

Deciphering the Preference and Predicting the Viability of Circular Permutations in Proteins

Circular permutation (CP) refers to situations in which the termini of a protein are relocated to other positions in the structure. CP occurs naturally and has been artificially created to study protein function, stability and folding. Recently CP is increasingly applied to engineer enzyme structure and function, and to create bifunctional fusion proteins unachievable by tandem fusion. CP is a complicated and expensive technique. An intrinsic difficulty in its application lies in the fact that not every position in a protein is amenable for creating a viable permutant. To examine the preferences of CP and develop CP viability prediction methods, we carried out comprehensive analyses of the sequence, structural, and dynamical properties of known CP sites using a variety of statistics and simulation methods, such as the bootstrap aggregating, permutation test and molecular dynamics simulations. CP particularly favors Gly, Pro, Asp and Asn. Positions preferred by CP lie within coils, loops, turns, and at residues that are exposed to solvent, weakly hydrogen-bonded, environmentally unpacked, or flexible. Disfavored positions include Cys, bulky hydrophobic residues, and residues located within helices or near the protein's core. These results fostered the development of an effective viable CP site prediction system, which combined four machine learning methods, e.g., artificial neural networks, the support vector machine, a random forest, and a hierarchical feature integration procedure developed in this work. As assessed by using the hydrofolate reductase dataset as the independent evaluation dataset, this prediction system achieved an AUC of 0.9. Large-scale predictions have been performed for nine thousand representative protein structures; several new potential applications of CP were thus identified. Many unreported preferences of CP are revealed in this study. The developed system is the best CP viability prediction method currently available. This work will facilitate the application of CP in research and biotechnology

CHARACTERIZATION OF A RAT ORAL SQUAMOUS-CELL CARCINOMA CELL-LINE UHG-RAC-'93 INDUCED BY 4-NITROQUINOLINE-1-OXIDE IN-VIVO

This study describes several characteristics of a cell line, UHG-RaC '93 derived from rat oral squamous cell carcinoma induced by the carcinogen 4-nitroquinoline-1-oxide (4NQO), The cell Line was established from explant cultures without support of fibroblast feeder cells and continued for > 30 passages, UHG-RaC '93 had a high mitotic rate with a population doubling time of 25 h and a high rate of squame production, The first passage had a low colony-forming efficiency in agarose gel, whereas later passages did not grow at all in semi-solid medium, Phenotype selection was furthermore apparent from a gradual increase of the trypsin-detachment time, Cytogenetic analysis showed that UHG-RaC '93 was hypotetraploid with an average of 74 chromosomes, Abnormalities compared to the normal karyotype were assessed and consisted mainly of breakpoints at (1)(q5?3), (3)(p1), (3)(q11q23), (11)(p?11), (13)(p13) and a derivative (12)t(12;13)(q10;q10). The karyotype remained stable for at least 26 passages, The expression of typical epithelioid markers like cytokeratins and desmoglein corresponded with normal rat oral keratinocytes, However expression of alpha 6 beta 4-integrin was altered, Squame production, immunophenotype and anchorage dependency indicated that UHG-RaC '93 had the same features of a well-differentiated carcinoma with a low degree of agressiveness as the original tumour. The stable karyotype of this cell line provides a basis for further analysis of the effect of 4NQO on the genotype, phenotype and behaviour of rat oral keratinocytes