Dynamic Analysis Of An 8000 HP Steam Turbine Operating Near Its Second Critical Speed.

LecturePg. 79-92A rotordynamics analysis of an 8000 hp steam turbine which drives an ethylene compressor is presented. This machine characteristically exhibited increasing vibration levels with increasing speed, in the upper portion of the speed range. It was suspected that this ramping vibration was due to operation near a critical speed. The purpose of this analysis was to identify the source of this high vibration with the present rotor and hearings and then to determine the best solution to the problem. The computer analysis determined that the original rotor/bearing system was operating near the second critical speed. The predicted peaks were within nine percent to thirteen percent of miming speed (8400 cpm). The optimum solution was to shorten the shaft at the governor end and replace the bearings. The shaft modification consisted of cutting off the governor worm gear assembly and replacing it with an electronic governor disk. This new bearing design was also a four-shoe tilting pad journal bearing, but it had longer pads and higher preload than the existing design. Because there was concern about coupling gear tooth lock-up in the original design, a dry, flexible-element coupling design was evaluated. The coupling change was also of interest because of its potential effect on moving the second critical speed. However, in this ease, the analysis determined that the rotor vibration characteristics were very close with either the existing gear coupling or the dry coupling. Therefore, the justification fo r changing couplings would be that the dry coupling would not be susceptible to drive tooth lockup and unbalance eccentricity due to tooth wear

Multi-Omics of Tomato Glandular Trichomes Reveals Distinct Features of Central Carbon Metabolism Supporting High Productivity of Specialized Metabolites

Glandular trichomes are metabolic cell factories with the capacity to produce large quantities of secondary metabolites. Little is known about the connection between central carbon metabolism and metabolic productivity for secondary metabolites in glandular trichomes. To address this gap in our knowledge, we performed comparative metabolomics, transcriptomics, proteomics, and (13)C-labeling of type VI glandular trichomes and leaves from a cultivated (Solanum lycopersicum LA4024) and a wild (Solanum habrochaites LA1777) tomato accession. Specific features of glandular trichomes that drive the formation of secondary metabolites could be identified. Tomato type VI trichomes are photosynthetic but acquire their carbon essentially from leaf sucrose. The energy and reducing power from photosynthesis are used to support the biosynthesis of secondary metabolites, while the comparatively reduced Calvin-Benson-Bassham cycle activity may be involved in recycling metabolic CO2 Glandular trichomes cope with oxidative stress by producing high levels of polyunsaturated fatty acids, oxylipins, and glutathione. Finally, distinct mechanisms are present in glandular trichomes to increase the supply of precursors for the isoprenoid pathways. Particularly, the citrate-malate shuttle supplies cytosolic acetyl-CoA and plastidic glycolysis and malic enzyme support the formation of plastidic pyruvate. A model is proposed on how glandular trichomes achieve high metabolic productivity

Combined 15N-Labeling and TandemMOAC Quantifies Phosphorylation of MAP Kinase Substrates Downstream of MKK7 in Arabidopsis

Reversible protein phosphorylation is a widespread posttranslational modification that plays a key role in eukaryotic signal transduction. Due to the dynamics of protein abundance, low stoichiometry and transient nature of protein phosphorylation, the detection and accurate quantification of substrate phosphorylation by protein kinases remains a challenge in phosphoproteome research. Here, we combine tandem metal-oxide affinity chromatography (tandemMOAC) with stable isotope 15N metabolic labeling for the measurement and accurate quantification of low abundant, transiently phosphorylated peptides by mass spectrometry. Since tandemMOAC is not biased toward the enrichment of acidophilic, basophilic, or proline-directed kinase substrates, the method is applicable to identify targets of all these three types of protein kinases. The MKK7-MPK3/6 module, for example, is involved in the regulation of plant development and plant basal and systemic immune responses, but little is known about downstream cascade components. Using our here described phosphoproteomics approach we identified several MPK substrates downstream of the MKK7-MPK3/6 phosphorylation cascade in Arabidopsis. The identification and validation of dynamin-related protein 2 as a novel phosphorylation substrate of the MKK7-MPK3/6 module establishes a novel link between MPK signaling and clathrin-mediated vesicle trafficking