Technology and benefits of aircraft counter rotation propellers

Results are reported of a NASA sponsored analytical investigation into the merits of advanced counter rotation propellers for Mach 0.80 commercial transport application. Propeller and gearbox performance, acoustics, vibration characteristics, weight, cost and maintenance requirements for a variety of design parameters and special features were considered. Fuel savings in the neighborhood of 8 percent relative to single rotation configurations are feasible through swirl recovery and lighter gearboxes. This is the net gain which includes a 5 percent acoustic treatment weight penalty to offset the broader frequency spectrum noise produced by counter rotation blading

Autoinhibition of TBCB regulates EB1-mediated microtubule dynamics

Tubulin cofactors (TBCs) participate in the folding, dimerization, and dissociation pathways of the tubulin dimer. Among them, TBCB and TBCE are two CAP-Gly domain-containing proteins that interact and dissociate the tubulin dimer. Here we show how TBCB localizes at spindle and midzone microtubules during mitosis. Furthermore, the motif DEI/M-COO– present in TBCB, which is similar to the EEY/F-COO– element characteristic of EB proteins, CLIP-170, and α-tubulin, is required for TBCE–TBCB heterodimer formation and thus for tubulin dimer dissociation. This motif is responsible for TBCB autoinhibition, and our analysis suggests that TBCB is a monomer in solution. Mutants of TBCB lacking this motif are derepressed and induce microtubule depolymerization through an interaction with EB1 associated to microtubule tips. TBCB is also able to bind to the chaperonin complex CCT containing α-tubulin, suggesting that it could escort tubulin to facilitate its folding and dimerization, recycling or degradation

Phosphorylation controls autoinhibition of cytoplasmic linker protein-170

Author Posting. © American Society for Cell Biology, 2010. This article is posted here by permission of American Society for Cell Biology for personal use, not for redistribution. The definitive version was published in Molecular Biology of the Cell 21 (2010): 2661-2673, doi:10.1091/mbc.E09-12-1036.Cytoplasmic linker protein (CLIP)-170 is a microtubule (MT) plus-end-tracking protein that regulates MT dynamics and links MT plus ends to different intracellular structures. We have shown previously that intramolecular association between the N and C termini results in autoinhibition of CLIP-170, thus altering its binding to MTs and the dynactin subunit p150Glued (J. Cell Biol. 2004: 166, 1003–1014). In this study, we demonstrate that conformational changes in CLIP-170 are regulated by phosphorylation that enhances the affinity between the N- and C-terminal domains. By using site-directed mutagenesis and phosphoproteomic analysis, we mapped the phosphorylation sites in the third serine-rich region of CLIP-170. A phosphorylation-deficient mutant of CLIP-170 displays an "open" conformation and a higher binding affinity for growing MT ends and p150Glued as compared with nonmutated protein, whereas a phosphomimetic mutant confined to the "folded back" conformation shows decreased MT association and does not interact with p150Glued. We conclude that phosphorylation regulates CLIP-170 conformational changes resulting in its autoinhibition.This work was supported by National Institutes of Health grant GM-25062 (to G.G.B.); Netherlands Organization for Scientific Research grants (to A. A. and N. G.); a Cancer Genomics Centre grant (to J.v.H.); and Presidential Program of Russian Academy of Sciences and RFBP grant 05-04-4915 (to E.S.N.)

Vibration monitoring of bridges

Traditional visual inspection tools, which are typically carried out annually, can only detect obvious damages like disruption, cracks or rust on the surface of bridges. Advanced non-destructive and destructive inspection tools are usually applied when visual inspection can’t provide sufficient information. Besides these techniques engineering surveyors can conduct geometric deformation analysis that provides additional information for damage detection of structures. The implementation of appropriate methods for data acquisition and analysis to detect changes to the material, geometric and dynamic characteristics of structures is summarised under the term Structural Health Monitoring (SHM). The essential idea of SHM is to determine a normal behaviour of undamaged structures and to obtain qualitative conclusions from changes of this behaviour related to the current health status. Information about changes within the dynamic characteristics of structures can be detected by applying accelerometers, which are a component of Ambient Vibration Methods (AVM) as an integral part of SHM. Analysis of acceleration measurements can derive natural frequencies that depend on weight, material, stress and strain as well as the geometry of the object. Hence this data can be used to derive additional information about the capacity and condition of a structure. In this paper we present a measurement system based on low-cost accelerometers that nevertheless performs measurements with high accuracy. This autonomously operatable device features a memory card slot, an internal battery, a waterproof housing and temperature resistant components. Additionally real time data transfer can be obtained via wireless LAN or USB connection to a computer. All necessary steps of data acquisition, processing and interpretation of vibration monitoring will be presented on a practical example

Synthetic, Structural, and Electrochemical Studies of Edge-Bridged Open Ferrocenes

The syntheses of the new compounds Fe(3-Me3Si-6,6-dmch)2, 2, and Fe[3-(i-Pr)3Si-6,6-dmch]2, 3, are reported, along with X-ray structural studies of these species, and of the previously reported Fe(1,3,5,6-temch)2 (dmch = dimethylcyclohexadienyl; temch = tetramethylcyclohexadienyl). Each species crystallized in something close to the expected gauche-eclipsed conformation. In accord with previous work on Fe(6,6-dmch)2, but in contrast to results for open ferrocenes such as Fe(2,4-C7H11)2 (C7H11 = dimethylpentadienyl), the three species under study undergo reversible one-electron oxidations at room temperature to stable 17-electron cations, with potentials for oxidation being more favorable than that for ferrocene by 0.51–0.78 V. The edge-bridged open ferrocenes also react in a 1:1 ratio with TCNE (TCNE = tetracyanoethylene), yielding salts that were shown spectroscopically to contain the expected cationic 17-electron metal complexes and the TCNE radical anion