Rotor fragment protection program: Statistics on aircraft gas turbine engine rotor failures that occurred in US commercial aviation during 1979

Statistical information relating to the number of gas turbine engine rotor failures which occurred during 1979 in commercial aviation service use is provided. The predominant failure mode involved blade fragments, 84 percent of which were contained. No uncontained disk failures occurred and although fewer rotor rim and seal failures occurred, 100 percent and 50 percent, respectively, were uncontained. Sixty-eight percent of the 157 rotor failures occurred during the take-off and climb stages of flight

Rotor burst protection program: Statistics on aircraft gas turbine engine rotor failures that occurred in US commercial aviation during 1975

Statistics on gas turbine rotor failures that have occurred in U.S. commercial aviation during 1975 are presented. The compiled data were analyzed to establish: (1) The incidence of rotor failures and the number of contained and uncontained rotor bursts; (2) The distribution of rotor bursts with respect to engine rotor component; i.e., fan, compressor or turbine; (3) The type of rotor fragment (disk, rim or blade) typically generated at burst; (4) The cause of failure; (5) The type of engines involved; and (6) The flight condition at the time of failure

Rotor burst protection program: Experimentation to provide guidelines for the design of turbine rotor burst fragment containment rings

Empirical guidelines for the design of minimum weight turbine rotor disk fragment containment rings made from a monolithic metal were generated by experimentally establishing the relationship between a variable that provides a measure of containment ring capability and several other variables that both characterized the configurational aspects of the rotor fragments and containment ring, and had been found from exploratory testing to have had significant influence on the containment process. Test methodology and data analysis techniques are described. Results are presented in graphs and tables

Catalytic Upgrading of Aromatic Oxygenates Related to Lignin

Lignin is one component of lignocellulosic biomass and is the only renewable, naturally-occurring source of aromatics in the world. However, lignin also provides a highly-oxygenated, complex, heterogeneous structure making the procurement of isolated aromatic molecules quite difficult. There has been extensive research in recent years to develop approaches to catalytically breakdown the lignin polymer into monomeric units. This works aims to develop a number of catalytic techniques for the upgrading of these monomeric units of lignin to produce means for producing chemical building blocks as well as suitable fuels from biomass sources. A method for the silanolysis of alcohols has been developed using a non-corrosive base catalyst, K2CO3. Chapter 2 details the reactions between a variety of alcohols and hydrosilanes to generate silyl ethers under mild conditions. These mild conditions allow for a wide substrate scope of alcohols to be explored due to a high functional group tolerance. Many of the alcohols that have successfully been silylated in this work are aromatic units. In total, 25 silylated alcohols were prepared through use of 5 different hydrosilanes. This silylation process is successful in the presence of reactive C–H bonds. The silylated alcohols prepared in this work have the potential to be used in polymer synthesis as well as to be used in hydrodeoxygenation reactions that would otherwise be difficult to perform. The aim of Chapter 3 is to explore the hydrodeoxygenation capabilities of the homogeneous transition metal catalysts, (2,2′:6′,2′′-terpyridine)nickel(II) hexafluorophosphate and chloro(2,2′:6′,2′′-terpyridine)palladium(II) chloride. The latter exhibited excellent activity and performed completely selective hydrodeoxygenation of benzylic oxygenates under very mild conditions. This catalysis was also observed at room temperature. The results of this work indicate a single-site molecular catalyst, which leads to the complete selectivity and lack of side product formation. In Chapter 4, the development of heterogeneous single-site molecular complexes is explored for the selective hydrodeoxygenation of benzylic oxygenates. The catalysts prepared are direct modifications to the successful catalyst in Chapter 3. Chloro(2,2′:6′,2′′- terpyridine-4′-carboxylic acid)palladium(II) chloride and chloro(-([2,2′:6′,2′′-terpyridin]- 4′-yl) benzoic acid)palladium(II) chloride, were synthesized and used to modify the surface of amorphous silicon dioxide to generate a hybrid molecular/heterogeneous catalyst. The hybrid catalytic system exhibited excellent activities and selectivities for hydrodeoxygenation while displaying the ability to recycle through multiple catalytic reactions. Spectroscopic techniques indicate that the molecular catalyst is present on the surface of SiO2 and the formation of unwanted metallic Pd nanoparticles can be avoided. Post reaction analysis of the surface-modified oxide catalysts confirmed prolonged molecular integrity of the catalysts and sustained binding of the catalysts to the oxide surface when nonpolar solvents were employed for reactions

Rotor fragment protection program: Statistics on aircraft gas turbine ngine rotor failures that occurred in U.S. commercial aviation during 1978

This report presents statistical information relating to the number of gas turbine engine rotor failures which occurred in commercial aviation service use. The predominant failure involved blade fragments, 82.4 percent of which were contained. Although fewer rotor rim, disk, and seal failures occurred, 33.3%, 100% and 50% respectively were uncontained. Sixty-five percent of the 166 rotor failures occurred during the takeoff and climb stages of flight

Rotor burst protection program: Statistics on aircraft gas turbine engine rotor failures that occurred in US commercial aviation during 1972

Based on FAA data, results are presented that establish (1) the incidence of rotor failure, (2) the type of fragments generated, (3) whether or not these fragments were contained, (4) the causes of failure, (5) where in the engine failure occurred, (6) what engines were affected and (7) what flight conditions prevailed at failure. The rate of uncontained rotor burst was considered to be significantly high. Blade fragments were generated in 95% of the rotor bursts, 20% of which were uncontained. Although fewer disk and rim fragment bursts occurred, none were contained

A high-­resolution monitoring network investigating stem growth of tropical forest trees.

Ref. B51D-0453

Protease Cleavage Leads to Formation of Mature Trimer Interface in HIV-1 Capsid

During retrovirus particle maturation, the assembled Gag polyprotein is cleaved by the viral protease into matrix (MA), capsid (CA), and nucleocapsid (NC) proteins. To form the mature viral capsid, CA rearranges, resulting in a lattice composed of hexameric and pentameric CA units. Recent structural studies of assembled HIV-1 CA revealed several inter-subunit interfaces in the capsid lattice, including a three-fold interhexamer interface that is critical for proper capsid stability. Although a general architecture of immature particles has been provided by cryo-electron tomographic studies, the structural details of the immature particle and the maturation pathway remain unknown. Here, we used cryo-electron microscopy (cryoEM) to determine the structure of tubular assemblies of the HIV-1 CA-SP1-NC protein. Relative to the mature assembled CA structure, we observed a marked conformational difference in the position of the CA-CTD relative to the NTD in the CA-SP1-NC assembly, involving the flexible hinge connecting the two domains. This difference was verified via engineered disulfide crosslinking, revealing that inter-hexamer contacts, in particular those at the pseudo three-fold axis, are altered in the CA-SP1-NC assemblies compared to the CA assemblies. Results from crosslinking analyses of mature and immature HIV-1 particles containing the same Cys substitutions in the Gag protein are consistent with these findings. We further show that cleavage of preassembled CA-SP1-NC by HIV-1 protease in vitro leads to release of SP1 and NC without disassembly of the lattice. Collectively, our results indicate that the proteolytic cleavage of Gag leads to a structural reorganization of the polypeptide and creates the three-fold interhexamer interface, important for the formation of infectious HIV-1 particles. © 2012 Meng et al