145 research outputs found
Heat transfer in the tip region of a rotor blade simulator
The measurement of mass transfer from cavities is discussed with emphasis on the effect of cavity orientations relative to the main flow direction. A finite difference computation for turbulent air flow and heat transfer over a two-dimensional shrouded rectangular cavity is discussed
Calculation of external-internal flow fields for mixed-compression inlets
Supersonic inlet flows with mixed external-internal compressions were computed using a combined implicit-explicit (Beam-Warming-Steger/MacCormack) method for solving the three-dimensional unsteady, compressible Navier-Stokes equations in conservation form. Numerical calculations were made of various flows related to such inlet operations as the shock-wave intersections, subsonic spillage around the cowl lip, and inlet started versus unstarted conditions. Some of the computed results were compared with wind tunnel data
Heat transfer in the tip region of a rotor blade simulator
The objective of this study of heat transfer in the tip region of a rotor blade simulator is to acquire, through experimental and computational approaches, improved understanding of the nature of the flow and convective heat transfer in the blade tip region. Such information should enable designers to make more accurate predictions of performance and durability, and should support the future development of improved blade tip cooling schemes
Heat transfer in the tip region of a rotor blade simulator
In gas turbines, the blades of axial turbine stages rotate in close proximity to a stationary peripheral wall. Differential expansion of the turbine wheel, blades, and the shroud causes variations in the size of the clearance gap between blade tip and stationary shroud. The necessity to tolerate this differential thermal expansion dictates that the clearance gap cannot be eliminated altogether, despite accurate engine machining. Pressure differences between the pressure and suction sides of a blade drives a flow through the clearance gap. This flow, the tip leakage flow, is detrimental to engine performance. The primary detrimental effect of tip leakage flow is the reduction of turbine stage efficiency, and a second is the convective heat transfer associated with the flow. The surface area at the blade tip in contact with the hot working gas represents an additional thermal loading on the blade which, together with heat transfer to the suction and pressure side surface area, must be removed by the blade internal cooling flows. Experimental results concerned with the local heat transfer characteristics on all surfaces of shrouded, rectangular cavities are reported. A brief discussion of the mass transfer system used is given
Enhanced magnetic response of fluids using self-assembled petal-like iron oxide particles
Using self-assembled iron oxide (SAIO) particles with petal-like morphology, aqueous fluids containing magnetic particles were prepared and the effect of hierarchical particle surface on the viscoelasticity under magnetic was investigated. The fluids consisting of self-assembled iron oxide particles exhibit highly tunable viscoelasticity which is controlled by applying external magnetic field. A difference between SAIO particles and spherical particles is explained by the fact that surface features of the self-assembled particles increased the network strength between particles in the fluids. © 2010 American Institute of Physics
CD8+ T Cells Mediate the Athero-Protective Effect of Immunization with an ApoB-100 Peptide
Immunization of hypercholesterolemic mice with selected apoB-100 peptide antigens reduces atherosclerosis but the precise immune mediators of athero-protection remain unclear. In this study we show that immunization of apoE (-/-) mice with p210, a 20 amino acid apoB-100 related peptide, reduced aortic atherosclerosis compared with PBS or adjuvant/carrier controls. Immunization with p210 activated CD8+ T cells, reduced dendritic cells (DC) at the site of immunization and within the plaque with an associated reduction in plaque macrophage immunoreactivity. Adoptive transfer of CD8+ T cells from p210 immunized mice recapitulated the athero-protective effect of p210 immunization in naïve, non-immunized mice. CD8+ T cells from p210 immunized mice developed a preferentially higher cytolytic response against p210-loaded dendritic cells in vitro. Although p210 immunization profoundly modulated DCs and cellular immune responses, it did not alter the efficacy of subsequent T cell dependent or independent immune response to other irrelevant antigens. Our data define, for the first time, a role for CD8+ T cells in mediating the athero-protective effects of apoB-100 related peptide immunization in apoE (-/-) mice
Calculation of reliability and probability of trouble-free operation of elements of the designed product
Enhanced Neointima Formation Following Arterial Injury in Immune Deficient Rag-1−/− Mice Is Attenuated by Adoptive Transfer of CD8+ T cells
T cells modulate neointima formation after arterial injury but the specific T cell population that is activated in response to arterial injury remains unknown. The objective of the study was to identify the T cell populations that are activated and modulate neointimal thickening after arterial injury in mice. Arterial injury in wild type C57Bl6 mice resulted in T cell activation characterized by increased CD4+CD44hi and CD8+CD44hi T cells in the lymph nodes and spleens. Splenic CD8+CD25+ T cells and CD8+CD28+ T cells, but not CD4+CD25+ and CD4+CD28+ T cells, were also significantly increased. Adoptive cell transfer of CD4+ or CD8+ T cells from donor CD8−/− or CD4−/− mice, respectively, to immune-deficient Rag-1−/− mice was performed to determine the T cell subtype that inhibits neointima formation after arterial injury. Rag-1−/− mice that received CD8+ T cells had significantly reduced neointima formation compared with Rag-1−/− mice without cell transfer. CD4+ T cell transfer did not reduce neointima formation. CD8+ T cells from CD4−/− mice had cytotoxic activity against syngeneic smooth muscle cells in vitro. The study shows that although both CD8+ T cells and CD4+ T cells are activated in response to arterial injury, adoptive cell transfer identifies CD8+ T cells as the specific and selective cell type involved in inhibiting neointima formation
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Materials and Component Development for Advanced Turbine Systems
In order to meet the 2010-2020 DOE Fossil Energy goals for Advanced Power Systems, future oxy-fuel and hydrogen-fired turbines will need to be operated at higher temperatures for extended periods of time, in environments that contain substantially higher moisture concentrations in comparison to current commercial natural gas-fired turbines. Development of modified or advanced material systems, combined with aerothermal concepts are currently being addressed in order to achieve successful operation of these land-based engines. To support the advanced turbine technology development, the National Energy Technology Laboratory (NETL) has initiated a research program effort in collaboration with the University of Pittsburgh (UPitt), and West Virginia University (WVU), working in conjunction with commercial material and coating suppliers as Howmet International and Coatings for Industry (CFI), and test facilities as Westinghouse Plasma Corporation (WPC) and Praxair, to develop advanced material and aerothermal technologies for use in future oxy-fuel and hydrogen-fired turbine applications. Our program efforts and recent results are presented
Flavonoids in prevention of diseases with respect to modulation of Ca-pump function
Flavonoids, natural phenolic compounds, are known as agents with strong antioxidant properties. In many diseases associated with oxidative/nitrosative stress and aging they provide multiple biological health benefits. Ca2+-ATPases belong to the main calcium regulating proteins involved in the balance of calcium homeostasis, which is impaired in oxidative/nitrosative stress and related diseases or aging. The mechanisms of Ca2+-ATPases dysfunction are discussed, focusing on cystein oxidation and tyrosine nitration. Flavonoids act not only as antioxidants but are also able to bind directly to Ca2+-ATPases, thus changing their conformation, which results in modulation of enzyme activity
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