Wright-Patterson Air Force Base

About: Wright-Patterson Air Force Base is a other organization based out in Wright-Patterson AFB, Ohio, United States. It is known for research contribution in the topics: Laser & Microstructure. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

The kinetics of static globularization of Ti-6Al-4V

Abstract: The kinetics of the evolution of the lamellar-colony microstructure to an equiaxed morphology during heat treatment of a hot-worked, two-phase titanium alloy were established. For this purpose, the alpha/beta alloy Ti-6Al-4V was isothermally upset forged at 900 °C or 955 °C and subsequently annealed for times ranging from 0.5 to 100 hours. The degree of the breakup of alpha-phase lamellae into lower-aspect-ratio grains during static annealing was measured and related to the imposed strain estimated using finite-element analysis (FEA). The kinetics of the static globularization of the alpha phase were found to depend on the amount of strain and the annealing temperature but were not affected by the specific deformation temperature in the 900 °C to 955 °C range. These results demonstrated that deformation-induced dislocation substructure has a small effect on the static-globularization process. In addition, the relative globularization kinetics at 900 °C and 955 °C were rationalized in terms of classical coarsening theory.

Biological And Health Effects Of Exposure To Kerosene-Based Jet Fuels And Performance Additives

Abstract: Over 2 million military and civilian personnel per year (over 1 million in the United States) are occupationally exposed, respectively, to jet propulsion fuel-8 (JP-8), JP-8 +100 or JP-5, or to the civil aviation equivalents Jet A or Jet A-1. Approximately 60 billion gallons of these kerosene-based jet fuels are annually consumed worldwide (26 billion gallons in the United States), including over 5 billion gallons of JP-8 by the militaries of the United States and other NATO countries. JP-8, for example, represents the largest single chemical exposure in the U.S. military (2.53 billion gallons in 2000), while Jet A and A-1 are among the most common sources of nonmilitary occupational chemical exposure. Although more recent figures were not available, approximately 4.06 billion gallons of kerosene per se were consumed in the United States in 1990 (IARC, 1992). These exposures may occur repeatedly to raw fuel, vapor phase, aerosol phase, or fuel combustion exhaust by dermal absorption, pulmonary inhalation,...

Aeroelastic flutter and divergence of stiffness coupled, graphite/epoxy cantilevered plates

Abstract: An analytical and experimental investigation was conducted to determine the aeroelastic flutter and divergence behavior of unswept, rectangular wings simulated by graphite/epox y, cantilevered plates with various amounts of bending-torsi on stiffness coupling. The analytical approach incorporated a Rayleigh-Ritz energy formulation and unsteady, incompressible two-dimensional aerodynamic theory. Flutter and divergence velocities were obtained using the \ -g method and compared to results of low-speed wind tunnel tests. Stall flutter behavior was also examined experimentally. There was good agreement between analytical and experimental results. Wings with negative stiffness coupling exhibited divergence, while positive coupling delayed the onset of stall flutter.

Cutting Edge: IL-4-Mediated Protection of Primary B Lymphocytes from Apoptosis via Stat6-Dependent Regulation of Glycolytic Metabolism

Abstract: IL-4 prevents the death of naive B lymphocytes through the up-regulation of antiapoptotic proteins such as Bcl-x(L). Despite studies implicating glucose utilization in growth factor-dependent survival of hemopoietic cells, the role of glucose energy metabolism in maintaining B cell viability by IL-4 is unknown. We show that IL-4 triggers glucose uptake, Glut1 expression, and glycolysis in splenic B cells; this is accompanied by increased cellular ATP. Glycolysis inhibition results in apoptosis, even in the presence of IL-4. IL-4-induced glycolysis occurs normally in B cells deficient in insulin receptor substrate-2 or the p85alpha subunit of PI3K and is not affected by pretreatment with PI3K or MAPK pathway inhibitors. Stat6-deficient B cells exhibit impaired IL-4-induced glycolysis. Cell-permeable, constitutively active Stat6 is effective in restoring IL-4-induced glycolysis in Stat6-deficient B cells. Therefore, besides controlling antiapoptotic proteins, IL-4 mediates B cell survival by regulating glucose energy metabolism via a Stat6-dependent pathway.

Crack Initiation in Unidirectional Brittle-Matrix Composites

Abstract: This paper describes the initiation of matrix cracking for glass and glass-ceramic matrix composites reinforced with small-diameter silicon carbide and carbon fibers under uniaxial tensile loading. Acoustic emission, replication, and optical microscopy in conjunction with stress-strain curves are employed to detect the initiation of matrix cracking. The proportional limit of the stress-strain curve is found to overestimate the initiation of matrix cracking in the material systems studied. The matrix cracking iniates at axial strains from 0.07% to 0.15%. The ACK model overestimates the initiation of the matrix cracking for the material systems studied in this paper.